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Mary Agnes LEIDER





Classification: Murderer
Characteristics: Threw her 3-year-old daughter out of a moving pickup truck
Number of victims: 1
Date of murder: December 3, 2012
Date of birth: 1988
Victim profile: Tennielle Big Day, 3 (her daughter)
Method of murder: Thrown out of a truck going 50 miles per hour
Location: Hardin, Big Horn County, Montana, USA
Status: Sentenced to 21 years and 10 months in prison without chance of parole on October 23, 2013

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Montana woman sentenced for death of 3-year-old daughter

By Victoria Fregoso

October 23, 2013

BILLINGS - Mary Agnes Leider of Saint Xavier, who threw her 3-year-old daughter out of a moving pickup truck last December, was sentenced on Tuesday to just under 22 years in prison.

Leider, 25, of Saint Xavier was sentenced to 262 months in prison by U.S. District Court Judge Donald Molloy.

Tenielle Big Day, 3, died when she was thrown out of a truck going 50 miles per hour on Montana Highway 313 south of Hardin.

Leider had a blood alcohol content level that night of 0.24, which is three times the legal limit.

During the sentencing in federal court on Tuesday afternoon, Leider along with the victim's uncle and father made statements.

A federal public defender, David Merchant, said Leider has experienced stress, guilt, and shame. He requested Leider's sentence be set at 15 years to allow her more time to get her life in order after she is released.

Leider made a tearful statement explaining that she's sorry she caused family members to suffer: "Nothing can bring her back and I have to live with that."

Assistant U.S. Attorney Lori Suek described the crime as "unimaginable." She pushed for the maximum sentence of 262 months.

Heywood Big Day III, the child's uncle, also gave an emotional statement speaking on behalf his family members in the courtroom. He painted the picture of Tenielle's personality and the large role she played within the family and community.

The uncle explained Tenielle's grandparents, Heywood and Veronica Big Day, were the primary caregivers for the 3-year-old girl. Heywood recalled the day Leider picked up her daughter from the house. He said even though Tenielle didn't want to see her mother, they figured it would help Leider. But instead, they now feel a sense of guilt because they believe they should not have let her go.

"We cry ourselves to sleep because there is nowhere else to go," Heywood Big Day III said.

Tenielle's father, Tennison Big Day, also expressed the sadness and frustration the family has gone through.

Molloy said the family's statements and his review of the case made it hard for him to understand how a mother could kill her own child.

Leider also had a daughter who died in December of 2009, the judge noted, and he questioned if it's possible for Leider to be a good mother.

The judge also said he has been shocked by the amount of violent crime and alcohol abuse on the reservation since he began his temporary role as a federal judge in Billings. He said there is a need for someone within the Crow Tribe to step forward and tackle crime and substance abuse on the reservation.


Crow Reservation woman gets 21 years for throwing 3-year-old daughter from pickup

October 23, 2013

BILLINGS — A woman from Montana's Crow Indian Reservation was sentenced to more than two decades in prison for killing her daughter by throwing the 3-year-old out of a fast-moving pickup after an overnight drinking binge.

The judge overseeing the case called it "incomprehensible."

Mary Agnes Leider, of St. Xavier, was sentenced Tuesday to 21 years and 10 months in prison without chance of parole for second-degree murder in the December 2012 death of Tennielle Ameryl Big Day.

With dozens of relatives from both sides of the girl's family packed into a Billings courtroom, U.S. District Judge Donald Molloy said he wanted to keep the 25-year-old defendant from doing further harm and send a message about the dangers of alcohol abuse on the reservation.

He said that in 18 years on the bench, he had never encountered such depravity in a criminal case, and the details made him nauseous.

"How could a mother do this to her own child?" Molloy said. He said members of the tribe need to stand up and say "enough is enough. Stop the drinking and the drugs and the violence."

Authorities say Leider's daughter was in her lap as she rode in a pickup driven by her brother after a night of heavy drinking in the Hardin area. The vehicle was going at least 45 mph when Leider uttered an expletive, opened her door and threw the girl into the roadway.

Leider and two brothers had drunk a quart of gin and up to 60 beers in the hours leading up to Tennielle's death, Molloy said. The defendant later registered a blood-alcohol level more than three times the legal limit for driving.

She pleaded guilty in July.

The young girl's relatives wailed loudly as Molloy recounted the crash and described Tennielle's injuries: "Head and brain were smashed and spinal cord destroyed ... by the stupidity of her mother."

Leider sat passively, her head bowed, through most of the sentencing hearing. When given a chance to address the court, she offered no explanation for why she killed her daughter.

"Words can't explain anything," Leider said. "Nothing can bring her back and I have to live with that."

The victim's paternal relatives said their family would never forgive Leider and asked the court to impose a harsh sentence. Her father, Tennison Big Day, described Tennielle as a Lego-loving baby who liked to perform traditional Crow dances and was raised primarily by her grandparents.

The girl's uncle, Haywood Big Day II, described how the death reverberated through the Crow reservation, where children play a central role as the future of the tribe. He said the victim's grandparents blamed themselves for not keeping the girl away from Leider, who had previous drunken driving offenses and a longstanding problem with alcoholism.

The defendant's lawyer, public defender David Merchant, asked the court to show mercy by sentencing Leider to a 15-year prison term. But prosecutor Lori Suek said the extreme conduct in the case merited a term at the high end of sentencing guidelines, a recommendation Molloy adopted.

Leider also was ordered to pay $11,123 restitution to cover Tennielle's funeral costs and her father's lost wages.


St. Xavier woman pleads guilty to killing 3-year-old daughter

July 24, 2013

BILLINGS — A woman from Montana's Crow Reservation pleaded guilty Wednesday to killing her 3-year-old daughter by throwing her from a moving pickup truck after a night of drinking with her brothers.

Mary Agnes Leider, 25, of St. Xavier, pleaded guilty to second-degree murder in the December 2012 death of Tenielle Big Day. U.S. District Judge Donald Molloy scheduled sentencing for Oct. 22.

Leider faces up to life in prison. She remains in custody while awaiting sentencing.

Prosecutors say the girl died of severe head injuries caused by being thrown out of a vehicle moving between 45 and 51 mph.

Leider's brother told investigators they were driving around at about 4 a.m. on Dec. 3 when Leider opened the pickup door and threw the girl out onto the highway south of Hardin.

Leider said she was very intoxicated and was holding her daughter in her lap in the passenger seat.

"I remember being very upset, but I don't remember what it was about," Leider said in court. "I tried to get out of the truck and forgot my daughter was on my lap."

Tests showed Leider's blood-alcohol level was more than 0.24 percent.


Mary Agnes Leider Pleads Guilty in U.S. Federal Court

U.S. Attorney’s Office

July 24, 2013

The United States Attorney’s Office announced that during a federal court session in Billings on July 24, 2013, before U.S. District Judge Donald W. Molloy, Mary Agnes Leider, a 25-year-old resident of Crow Agency and an enrolled member of the Crow Tribe of Indians, pled guilty to second-degree murder. Sentencing has been set for October 22, 2013. She is currently detained.

In an Offer of Proof filed by Assistant U.S. Attorneys Jessica T. Fehr and Lori Harper Suek, the government stated it would have proved at trial the following:

On December 3, 2012, at approximately 4:06 a.m., 911 operators from the Big Horn County Sheriff’s Office began receiving phone calls that they identified as coming from the area of mile marker 11 on Highway 313, south of Hardin. Operators dispatched law enforcement and an ambulance in response.

When they arrived at the scene, law enforcement found Leider and her brother, A.L., sitting to the side of the road, crying uncontrollably. Leider told law enforcement that her baby was “gone” and had been hit by a vehicle. As additional law enforcement officers arrived, there was another 911 call that dispatched additional law enforcement to mile marker 19, Highway 313, to respond to another 911 emergency call regarding a deceased 3-year-old child. Upon arrival at the scene, law enforcement were met by G.D. and her son, W.L. G.D. is the mother of Leider, A.L., and W.L. G.D. took an officer to her car, where the officer found a 3-year-old female. The child was examined and appeared to already be deceased. The child was identified as Leider’s daughter.

Later on that day, law enforcement interviewed G.D. She advised that her daughter, Leider, and her two sons had been out partying during the evening of December 2, 2012, and had taken the victim with them. G.D. reported that she had repeatedly called and text messaged her children in order to have Leider come home with the victim, but Leider refused. Early in the morning hours of December 3, 2012, G.D. reported that she left to find Leider and the victim and was traveling towards Hardin. As she was traveling north on Highway 313, she saw Leider’s pickup traveling towards her. Both vehicles stopped, and G.D. saw that Leider’s pickup was being driven by W.L. W.L. told G.D. that something was wrong with the victim—Leider’s 3-year-old daughter. G.D. saw the victim in the backseat and realized she was not breathing and not responsive. W.L. told G.D. that Leider had thrown the victim from the pickup. When G.D. picked the victim up, she saw blood coming from the back of her head. She called an ambulance and put the victim in her car.

W.L. was interviewed by law enforcement and reported that he was driving Leider’s pickup early in the morning on December 3, 2012. W.L. reported that Leider was seated in the front passenger’s seat, with the victim on her lap. At the time, the victim was quiet but awake. While they were driving south towards St. Xavier, Leider opened the front passenger door with her right hand and threw the victim out of the moving pickup. W.L. and the reconstructionist from the Montana Highway Patrol estimated the truck was traveling between 45 and 51 miles per hour at the time the victim was thrown from the truck. W.L. stopped as fast as he could and threw Leider out of the truck with A.L. W.L. went back down the road behind the truck to where the victim was lying in the roadway. W.L. reported that he knew she was dead but carried her back to the truck and placed her in the backseat. He began driving towards home, leaving Leider and his brother A.L. by mile marker 11 where they were ultimately found by law enforcement a short time later.

Following the arrival of law enforcement at the scene, Leider was taken to Hardin Memorial Hospital to have her blood drawn and for treatment for abrasions to her face. Her blood alcohol level was found to be over a 0.24 when analyzed by the FBI Laboratory. While there, she alternated between saying “I killed my baby” and claiming that the group had a car accident and that was how the victim had died. When questioned by law enforcement, Leider admitted that she had been driving around and drinking with her brothers but claimed that she hit her face on the dashboard and could not recall how the victim was killed. Leider’s pickup was impounded and towed to a law enforcement facility for analysis. The right front passenger door was analyzed by a professional mechanic, and it was found that the door functioned properly.

An autopsy was conducted of the victim. Following the autopsy, the victim’s probable cause of death was determined to be severe head injuries caused when thrown from a moving motor vehicle.

The crime occurred within the exterior boundaries of the Crow Indian Reservation.

Leider faces possible penalties of life in prison, a $250,000 fine, and five years’ supervised release.

The investigation was a cooperative effort between the Bureau of Indian Affairs and the Federal Bureau of Investigation.


Mother denies murder charges in daughter’s death

February 26, 2013

Mary Agnes Leider, accused of throwing her toddler out of a moving pickup truck south of Hardin, denied murder charges Tuesday.

During a brief arraignment before U.S. Magistrate Judge Carolyn Ostby, Leider, 24, of St. Xavier, pleaded not guilty to second-degree murder.

Leider appeared in court earlier this month on a criminal complaint filed in the case. Second-degree murder, which is knowingly killing a person with malice aforethought, carries a maximum penalty of life in prison and a possible $250,000 fine.

Leider’s daughter, Tenielle Ameryl Big Day, 3, died Dec. 3 of blunt-force trauma, Big Horn County Coroner Terry Bullis said earlier.

Court records allege that Leider, who was in the front passenger seat of her pickup truck, which was being driven by her brother, Wally Leider, opened the door and threw her daughter onto Highway 313 on the Crow Reservation.

Law enforcement officers responded to a call shortly after 4 a.m. and found Leider and her brother, Arland Leider, sitting by the side of the road and crying. Officers responding to another call on the highway about eight miles away found Wally Lieder, the dead child and Georgiana Denny, the Leiders’ mother.

Wally Leider told investigators that while traveling south to St. Xavier, Mary Leider opened the passenger door and threw her daughter out. He stopped as fast as he could, removed his sister from the truck and went back down the road to where the child lay.

Mary Leider was taken to Hardin Memorial Hospital for treatment of facial abrasions and to have her blood drawn. Blood results showed her alcohol level was 0.24 percent, three times the legal limit for driving. She also gave conflicting statements about what happened.

Ostby continued Leider’s detention. The case will be heard by Chief U.S. District Judge Richard Cebull.


Mom allegedly threw toddler from moving vehicle

By Stephen Loiaconi -

February 8, 2013

Around 4 a.m. on December 3, 2012, authorities say 24-year-old Mary Agnes Leider sat in the front passenger seat of her Dodge pickup while her brother Wally drove down Highway 313 south of Hardin, Montana.

According to court documents, they had been out drinking that night and were on their way home. Mary's 3-year-old daughter Tennielle Big Day sat quietly on her lap.

Wally Leider later allegedly told authorities that as he drove Mary reached for the passenger door, opened it and threw Tennielle out of the moving vehicle. The child died from her injuries.

A federal criminal complaint for second-degree murder was filed against Mary Leider on Tuesday in connection with her daughter's death.

A probable cause affidavit stated that the Big Horn County Sheriff's Office received 911 calls at approximately 4:06 a.m. on December 3 from distraught individuals in the area of mile marker 11 on Highway 313. Responding officers found Mary Leider and her brother Arland sitting on the side of the road, "crying uncontrollably" the affidavit said.

At the time, Leider allegedly told the first deputy on the scene that her baby had been hit by a vehicle and was "gone," according to the affidavit. Soon after that, however, the deputy was dispatched to respond to another 911 call at mile marker 19 on the same road.

There, he was met by Wally Leider and their mother, Georgina Denny, who showed him Tennielle Big Day's lifeless body, court documents stated.

According to court documents, Mary Leider told authorities that she had been arguing with Wally while he was driving home and she kept telling him to slow down. She said he stopped the vehicle and she hit her face on the dashboard. She allegedly claimed she could not remember how Tennielle was injured after that.

Wally Leider allegedly told investigators that Mary threw Tennielle from the vehicle, the probable cause affidavit stated. He said he stopped the truck, got out and saw the girl lying in the road. He believed she was already dead, but he put her in the back seat and drove toward their home, leaving Mary and Arland behind, court documents stated.

According to the affidavit, Georgina Denny told officers she had gone out looking for her children and granddaughter, but she then saw Wally driving down Highway 313 in Mary's pickup truck. They both stopped and Wally showed her Tennielle, who was unresponsive and not breathing, in the truck. Denny said she saw blood coming from the back of the girl's head.

Mary Leider was taken to a hospital for treatment of facial abrasions and to have her blood drawn. An FBI lab determined that her blood alcohol level was higher than .24, the affidavit stated. While at the hospital, she allegedly alternated between claiming that her daughter died in a car accident and saying, "I killed my baby."

Investigators determined that the vehicle had not been in an accident.

Leider made her first court appearance on the second-degree murder complaint Wednesday and waived a preliminary hearing. A detention hearing has not been scheduled.

Court records indicate that Leider is a member of the Crow Tribe and that the crime occurred within the boundaries of the Crow Indian Reservation.

A spokesperson for the Montana U.S. Attorney's Office declined to discuss a possible motive or any other details of the case, citing the ongoing nature of the investigation. Prosecutors plan to go before a grand jury within 30 days and seek an indictment against Leider.

A federal public defender appointed to represent Leider did not return calls seeking comment on the case.

According to an obituary published in the Billings Gazette, Tennielle Big Day was "an active child who loved to play outdoors with her friends. She often enjoyed building castles with her Lego blocks. She loved to dance and was a traditional Crow dancer."


3-year-old’s death on highway investigated as homicide

By Clair Johnson -

December 20, 2012

The FBI is investigating the recent death of a 3-year-old girl, who is thought to have been tossed from a moving vehicle by her mother on U.S. Highway 313 south of Hardin, as a homicide.

The agency sought a warrant Wednesday to search a pickup truck registered to Mary Agnes Leider, 24, of Billings and St. Xavier. She is the mother of Tenielle Ameryl Big Day, 3.

The child died Dec. 3 from blunt-force trauma from a “vehicular incident,” Big Horn County Coroner Terry Bullis said earlier.

FBI spokeswoman Deborah Bertram in Salt Lake City declined to comment Thursday on the search warrant application, but earlier she said agents were in the midst of an ongoing investigation. The FBI has provided few details about the case.

However, the FBI’s search warrant application filed in U.S. District Court in Billings gives an account of what it suspects happened based on interviews with witnesses. Court records did not indicate when a search would be undertaken.

The truck is a purple 1999 Dodge pickup registered to Mary Agnes Leider. The search seeks hair, fibers, bodily fluids containing DNA and any item related to the pickup’s operation, the application said. The pickup is at Big Horn County’s impound yard in Hardin.

Tenielle Big Day was “allegedly thrown from a moving vehicle,” Larry J. McGrail II, an FBI special agent, said in the court document.

In an interview with investigators on Dec. 3, Wally Leider said his sister, Mary Leider, had thrown her daughter out of the pickup while he was driving, the agent said.

Mary Leider was sitting in the front seat with Tenielle on her lap, Wally Leider told investigators. The girl was “quiet but awake” when Mary Leider “opened the front passenger door with her right hand, and threw (Big Day) out of the pickup,” Wally Leider told investigators.

Wally Leider immediately stopped and Mary Leider got out of the pickup, the agent said. Wally Leider walked behind the pickup, where he found Tenielle and knew she was dead. He then picked up the child, put her in the back seat and drove toward his mother’s house.

Mary Leider told officers that she had been driving around with her daughter and drinking with her brothers when her brothers began arguing on the way home. She said she told Wally Leider to slow down. At some point he stopped the pickup and she hit her head on the dashboard.

Mary Leider also told officers that before hitting her head, her daughter was on her lap but that she couldn’t remember what had happened to the child when the pickup stopped or how her daughter got injured.

Three days later, Mary Leider was booked into the Yellowstone County jail on a warrant from Billings Municipal Court for revocation of a suspended sentence for traffic violations. She was released on Dec. 9.

Law enforcement officers learned something had happened Dec. 3 when the Big Horn County Sheriff’s Office started getting calls at 4:06 a.m. from people who were distraught and crying. The calls were tracked to an area near mile marker 11 on Highway 313 on the Crow Reservation. Officers and an ambulance responded.

A deputy sheriff found Mary Leider and her brother, Arland Leider, sitting by the side of the road, “crying uncontrollably,” the agent said. “Mary told the deputy that her baby was ‘gone’ and had been hit by a vehicle,” he said.

As more officers arrived, the deputy was sent farther along the highway to respond to a 911 call about a deceased 3-year-old. There, the deputy was met by Wally Leider and Georgiana Denny, the mother of Mary, Wally and Arland Leider. Denny took the deputy to her car, where Tenielle Big Day’s body had been placed. The pickup truck also was there.

Denny told investigators that her three children had been out partying while Tenielle Big Day was with them. Mary Leider had repeatedly refused Denny’s calls and text messages to return home with the child, she told officers.

Denny then started driving toward Hardin on Highway 313, looking for them. She stopped when she saw Mary Leider’s pickup approaching and Wally Leider was driving. Wally Leider told his mother that “something was wrong” with Tenielle and that his sister had thrown the child from the pickup. Denny called for an ambulance and placed the child in her car.



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