SAN DIEGO -- A former registered nurse at Children's Hospital, who allegedly molested a 4-year-old comatose girl under his care, pleaded not guilty Tuesday to sexual assault charges and 20 counts of distributing child pornography.

Christopher Alan Irvin, 32, was ordered held on $2 million bail and agreed not to practice nursing while his case was pending.

Irvin's arrest Friday night marked the second time in just over a month that a Children's Hospital employee has been charged with molesting children and dealing in child porn on the Internet.

Wayne Bleyle, 54, a former respiratory therapist at Children's Hospital, is charged with molesting two brain-damaged youngsters and trading in child pornography.

Outside the courtroom, Deputy District Attorney Laura Gunn said the cases are upsetting because, among other things, Children's is a highly-regarded institution.

"You can't help but sympathize with the people who work there," Gunn said.

Gunn told Superior Court Judge David Szumowski that Irvin admitted molesting the girl in the critical care unit where he worked.

She argued the defendant posed a danger to the community and was a flight risk.

During a search of Irvin's home, detectives found a journal detailing the defendant's obsession with children, the prosecutor said.

She said Irvin volunteered at Girl Scout events, wanted to adopt a little girl and volunteered at the Polinsky Children's Center.

Irvin wrote in one journal entry,: "'I easily and often fall in love with children,'" Gunn said.

The defendant said he was "unhappy and lonely" in San Diego and talked about moving back to Tallahassee, Fla., where he once worked, the prosecutor said.

Outside court, Gunn said Irvin had worked at Children's for two years and was the subject of an investigation by the San Diego Internet Crimes Against Children Task Force, who conducted searches at the defendant's work and residence last week.

Irvin is charged with molesting one child, and Gunn said she hoped "very much" that there aren't any more alleged victims who come to light.

The defendant, who was fired upon his arrest, is charged with two counts of committing a lewd act on a child under 14 and distributing child porn.

Gunn said the alleged victim has a rare disease and remains hospitalized in grave condition.

"She is a very ill child," the prosecutor said outside court.

Szumowski set a status conference for next Tuesday and a preliminary hearing for May 1.