WAUSAU – The Wausau baby sitter charged with killing a 2-month-old boy in her care tried to hide the infant's death from his mother and then went swimming at a Wausau hotel with her boyfriend and son, police say.

She dressed the baby in winter clothes and strapped him in a car seat, pretending he was alive during a trip to McDonald's and continuing the ruse when she gave the boy back to his mom, court documents said.

Marissa Tietsort, 28, was charged Friday with first-degree intentional homicide in the baby's death.

Family and friends of the 2-month-old boy filled the benches of a Marathon County courtroom wearing "Justice for Benson" T-shirt featuring a photo of the infant. Judge Jill Falstad issued a $500,000 cash bond and ordered that Tietsort not have any contact with children under 18 or contact with the victim's immediate family.

Tietsort has been in jail since October on a $250,000 cash bond in a separate child abuse case. If she is ever able to post bond, Tietsort is not allowed to leave Marathon County, the judge ruled. 

According to a criminal complaint, Tietsort knew the child had died while in her care but did not tell the baby's mother when she came to pick up her son. An autopsy shows the baby died of blunt force trauma to his head, the complaint said. 

The 2-month-old boy's mother dropped off the baby and his older brother at Tietsort's home on North Sixth Street in Wausau in the afternoon of Oct. 18. The infant was awake and Tietsort was the only adult at the home when the victim's mother left her children there, according to the complaint.

About two hours later, the baby's mom got a text from Tietsort letting her know that there was a story about herself on a local news outlet's website saying she had been charged with child abuse. Tietsort told the mother she was not allowed to be in contact with children and not to tell anyone she was watching her two sons. The mother came and picked up her sons about three hours later, according to the complaint. 

When the victim's mother came to pick up her infant and older son, the infant was seated in his car seat, wearing a snow suit with a hat pulled down over his eyes. The mother told police she believed her son was sleeping, as it was past 9 p.m., according to the complaint.

The victim's mother then brought her children to Northway Coin Laundry on West Third Street in Wausau, where she discovered her infant son was not breathing, cold to the touch and had stiff limbs. The mother immediately started doing CPR on her son while the mom's sister called 911. When officers from the Wausau Police Department arrived on the scene around 9:45 p.m., officers observed the infant "had an ashen skin tone, his jaw was clenched and his lips were blue," according to the complaint.

Police found Tietsort at the Plaza Hotel in Wausau at 4:15 a.m. on Oct. 19. She admitted that she had been watching the infant and his brother the day before and that the infant had died while she was watching him, according to the complaint. 

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Tietsort told police she did not kill the infant, but did not make any efforts to resuscitate him or get him medical help. She said she knew the baby was dead because he was cold to the touch but she did not check for a pulse, according to the complaint.

After realizing the baby had died, she dressed him in his snowsuit and hat, covered him with blankets and put him in his car seat. When Tietsort's boyfriend returned home around 6:30 p.m., she did not tell him the infant had died. Tietsort, her boyfriend, their son and the victim's son then went to eat at McDonald's. Tietsort brought the dead baby with them, the complaint states.

An autopsy determined the 2-month-old boy died of "blunt force head injuries with multiple impacts to the head," according to the complaint. The infant had at least three separate injuries to his head, which all occurred around the time of his death, forensic pathologist Robert Corliss opined. The boy also had significant injuries to his tailbone, which Corliss said was "fractured, broken off and displaced, indicating a significant amount of force was used."

After the 2-month-old's death, Tietsort was arrested on a child abuse charge from an incident that happened in August. According to court documents, the father of an 11-month-old girl told police that he believed Tietsort injured his child while she was baby-sitting her. Tietsort told the girl's parents that the girl had fallen off the couch while sleeping, which resulted in injuries to the face. However, doctors told the parents that the injuries, though superficial, were not consistent with a fall from that height, court documents said. 

In 2017, an infant was taken to the hospital with a bruised face and skull fracture. Tietsort told investigators that the infant's older sister had tried to take a bottle away from Tietsort while she fed him. She told police the bottle struck the infant, which caused the injury, according to court documents. She was never charged in that incident.

In 2010, Tietsort's boyfriend filed for temporary restraining orders after he told investigators she was abusing their two sons. Records show social services workers have removed four of Tietsort's children from her care and were unaware that she had given birth to her fifth child. Tietsort is now in the Marathon County Jail and pregnant with her sixth child . 

Tietsort is scheduled to be back in court at 1 p.m. on Jan. 18.