SAN DIEGO -- A man accused of molesting two teenage boys when they lived with him in San Diego in the late 1990s pleaded not guilty Monday to 30 counts of child molestation.

Steven Meredith Bimson, 64, was ordered held on $750,000 bail.

Bimson was found Aug. 18 semiconscious inside a rental car parked on the side of a Las Vegas freeway, with a hose running from the vehicle's exhaust pipe into the passenger compartment, according to the U.S. Marshal's Service.

Outside court Monday, Deputy District Attorney Wendy Patrick Mazzarella said she asked Judge David Szumowski for the high bail for several reasons, including the fact that there is a 40-year age difference between Bimson and his alleged victims, who were 13 and 14 at the time of the alleged molestations.

The prosecutor said the boys knew each other and lived with the defendant at different times for two or three years apiece.

The defendant engaged in a "horrible breach of trust" by taking in the victims and agreeing to care for them before molesting them, the prosecutor alleged.

"They lived with him as a father figure," she told reporters.

San Diego police began investigating Bimson in January based on a tip from Child Protective Services, and investigators subsequently identified five alleged victims.

The charges filed in San Diego reflect the defendant's alleged crimes against the two boys who lived with him in San Diego County, Patrick Mazzarella said.

Szumowski scheduled a readiness conference for Sept. 22 and a preliminary hearing for Oct. 20.