A 14-year-old boy is accused of attacking and killing a teacher at a state juvenile detention facility in Prince George's County.

The boy was arraigned Wednesday and the counts against him include first-degree murder, rape and other sex offenses. He is accused of sexually assaulting, beating and strangling 65-year-old Hannah Wheeling at the Cheltenham Youth Facility on Feb. 18.

Prosecutors are seeking to try the teen, who was 13 at the time, as an adult.

Wheeling was last seen administering a test to the boy at 4 p.m. the day before her partially clothed body was found outside her classroom, according to a source close to the investigation.

Three shirts, one with the suspect's initials, were found near the crime scene, according to information from the source, and blood stains and the boy's DNA were found on them.

The suspect's DNA also was found in Wheeling, according to the source.

Another Cheltenham staff member encountered the boy at about 5 p.m. on Feb. 17, according to the source, and said the boy was running up stairs near the crime scene unattended and looked nervous, sweaty and flushed.

Cheltenham holds youths awaiting trail in Prince George's, Anne Arundel, Calvert, Charles and St. Mary's counties. The suspect was housed there at the time of Wheeling's death, but has been moved to a facility in Western Maryland.

Allen Wolf, the boy's public defender, said the charges were a surprise because he was told Wednesday's court appearance would be a placement hearing on unrelated offenses.

"I walked in there this morning not knowing this was going to happen," he said.

The boy was originally sent to Cheltenham for burglary charges, Wolf said. He declined to discuss details.

Wolf said the boy is a juvenile, so he should be tried in juvenile court for the Wheeling case.

The boy's arraignment came a week after state House Minority Leader Anthony O'Donnell released a letter questioning why charges hadn't been filed.

But Glenn Ivey, the state's attorney for Prince George's County, said his office wasn't pressured to file charges.

"We appreciate the legislature's interest," he said, but added, "Politics is irrelevant for us."

Prosecutors asked Judge C. Philip Nichols to detain the boy on charges related to Wheeling's death, but Nichols declined to do so, saying the boy is already in custody for the other offenses.

The boy appeared in court Wednesday, but only spoke to answer the judge's questions with one-word responses.