Adderli Jose Cruz-Rosario (Montgomery County Police Department)

A Silver Spring man accused of throwing a toddler against a bedroom wall and sexually abusing four of her young siblings has agreed to plead guilty in the case and faces up to 57 years in prison, according to Montgomery County court documents.

Adderli Cruz-Rosario, 21, who was friends with the children’s mother and took care of the children during the day, was scheduled for trial at the end of the month. Prosecutors appeared to have lined up a strong witness — the toddler’s treating physician from Children’s National Medical Center — to bolster statements made to detectives by her siblings, according to the court filings.

Among the doctor’s findings: The girl, who was 19 months old when she was hospitalized, had suffered nine rib fractures; injuries to her brain, liver and pancreas; and overall symptoms consistent with being a battered child. Her 10-year-old brother had told investigators that he saw Cruz-Rosario punch the girl, force her onto the floor and pin her down with athletic weights to try to get her to sleep — prompting the boy to sneak back into the room to free her.

Three of the children told detectives that Cruz-Rosario had bitten and beaten them, court papers say. Three of the children said he sexually abused them, sometimes in the hallway or living room of their apartment at night. Medical tests confirmed injuries consistent with sexual abuse in two of the children, according to the court records.

“This is a very troubling case,” said Ramon Korionoff, a spokesman for the Montgomery County state’s attorney’s office, who said a plea agreement would spare the children from having to testify publicly. “We believe this defendant must be held accountable.”

Cruz-Rosario remains in the Montgomery County Detention Center, where he has been held for about 10 months, according to online court records. His attorney, Theresa Chernosky, declined to comment on Monday.

Cruz-Rosario was scheduled to make his plea Monday, but the snowstorm closed Montgomery’s courthouses. For the agreement to be final, Cruz-Rosario must admit guilt in court and the plea must be accepted by a judge.

In papers signed last week, Chernosky and prosecutor Jessica Hall stated that they had agreed to a deal in which Cruz-Rosario would plead guilty to five counts for acts that occurred in 2012 and 2013: physical abuse of the toddler, who was 16 to 19 months old at the time; and four counts of sexual abuse involving four children ages 5 to 11.

The case raised questions about how Cruz-Rosario could have acted and not been found out by the children’s mother, who also lived in the apartment. But experts in child abuse say it is common for abusers to use threats to keep information hidden, even from a parent, and there were long daytime stretches when the mother was at work.

In an earlier interview, the mother said Cruz-Rosario had cooked meals for the children, cleaned up after them and taken them swimming.

“Every minute, every day, I’m always thinking about what happened,” the woman had said. “If it did happen, why?”

She could not be reached for comment Monday.

For police, the case began on April 12, 2013, when detectives were notified of a possible abuse victim who had been taken to Holy Cross Hospital. The girl had facial bruising that appeared to have resulted from being grabbed or bitten. The toddler also had an elevated enzyme count, which can indicate organ damage. She was transferred to Children’s National Medical Center, where for two weeks she was unable to take food by mouth without experiencing pain and vomiting.

In court papers, prosecutors said that Maryland sentencing guidelines call for 29 to 57 years in prison for the five charges, and that they would not seek a sentence beyond that. Cruz-Rosario’s attorney, Chernosky, is free to seek a sentence below 29 years, according to the plea agreement.