A 13-month-old girl who died Friday after sustaining injuries while in the care of her mother's boyfriend was injured so badly that doctors had to remove a portion of her brain to ease the swelling.

Michael A. Rios, 22, of 176 Elizabeth St., Norwich, was arrested Monday and charged with first-degree manslaughter and risk of injury to a minor.

Rios gave police different versions on how the child was injured.

An autopsy indicated that she died of blunt head trauma, sustaining numerous injuries, including a subdural hematoma on the left side of her brain, bruising on her spinal cord, hemorrhaging in both optic nerves and a cut on the inside of both her upper and lower lips.

According to a warrant prepared by Norwich Detective Damon R. Wallace, he received a phone call Thursday from an investigator for the Department of Children and Families about an anonymous complaint from a nurse at The William W. Backus Hospital, who said the child was unresponsive and had bleeding on the brain.

Rios had taken the child to Backus and told personnel that she had fallen off a bed. There were no visible injuries. Life Star helicopter flew the child to the Connecticut Children's Medical Center, the warrant said.

Wallace went to the medical center and met with the DCF investigator, the victim's mother and Rios.

The mother said her daughter had an ear infection and was taking medicine for it but was otherwise healthy and happy.

During the surgery, doctors discovered the subdural hematoma. She died during the early-morning hours on Friday.

Rios told the detective he had slept over at the victim's mother's house Wednesday night. The woman went to work Thursday morning, and he was supposed to take the child to her day care in Montville, the warrant says.

He told police that he has known the mother for five years, but they had just started dating three months ago.

Rios said he was asleep until 9:30 a.m. He said he dressed the child while she slept and woke her up around 10:30 a.m.

He said he was in the kitchen to get the girl's medicine when he heard a "bang" from the bedroom. He said he saw the victim on the floor and that she was breathing "funny." He said he picked her up and took her to the hospital.

Wallace said before he spoke with Rios, Dr. Nina Livingston at the medical center spoke with Rios, who told her he did not attempt CPR.

"Dr. Livingston stated his explanation of events does not fully explain the extent of the victim's injuries," the warrant says.

Wallace said when he spoke to Rios again, Rios changed his story. This time, he said he would play with the girl, tossing her up in the air and catching her under her armpits. Rios said the victim's head would snap back and forth, but he would stop doing it once the little girl stopped laughing.

Rios said that on April 30, he was playing with the girl, tossing her in the air as usual but stopped because she seemed to stop enjoying it. They went to the bathroom to comb her hair. He said he sat her on the vanity next to the sink and that the girl became dizzy and fell into the sink, striking her head on the faucet. He said she cried for two minutes as he soothed her. He did not seek medical treatment for her, the warrant said.

Wallace spoke to the mother, who said they went to celebrate Rios' birthday last Wednesday at a restaurant in New London. She said she did not see him consume any alcohol. She told police she didn't allow Rios to care for the child alone until around April 21.

Rios said after the celebration they arrived at the victim's home at around 8 p.m., and he fell asleep in the car. He went inside around 10 p.m., where he found his girlfriend and the child asleep.

Rios continued to tell police the child had fallen off the bed, but this time he added that he had attempted to give the victim CPR.

Wallace told Rios that Livingston said his story is not consistent with the victim's injuries.

"Rios sank down in his seat and covered his face with his hand," the warrant said. "Rios stated that after the victim fell from the bed, he picked her up and 'shook her very hard' to get her to respond. ... Her breathing changed, more like a hiccup."

After signing his statement to police, Rios said, "I know it's wrong to shake a baby."

Rios was released after posting a $100,000 surety bond and is due to appear May 16 in Norwich Superior Court.

i.larraneta@theday.com