A man who baby-sat for two Rockville toddlers just before they died was charged yesterday with sexually abusing one of the children, the Montgomery County state's attorney said yesterday.

Timothy Conrad Phillips, 30, was charged with child abuse and second-degree sex offense after the Maryland state medical examiner determined that 13-month-old Amani Renee Robinson suffered from "sexual abuse of a severe nature," State's Attorney Douglas F. Gansler said yesterday.

Gansler said his office is awaiting final results on the cause and manner of Amani's death before deciding whether Phillips will face more charges. He has not been charged in the death of Amani or of Andre Michael Whitworth, 2.

Amani died Aug. 26 at Shady Grove Adventist Hospital after a 911 dispatcher was told the girl had drowned in the bathtub of her mother's Rockville home.

In February 1997, Andre died two days after his mother found him unconscious and badly beaten in his crib. Andre's death was ruled a homicide.

Both Andre and Amani lived in the same neighborhood as Phillips at the time of their deaths, and their mothers said they had been befriended by him.

Phillips surrendered to authorities Aug. 26 and was held at the Montgomery County Detention Center on an unrelated theft charge under $2,500 bond. The bond on the child abuse and sex offense charges is $250,000.

The medical examiner found evidence of multiple incidents of vaginal and rectal penetration of the girl, Gansler said.

Gansler said officials charged Phillips before the medical examiner's study was completed because they feared he would post bond for the theft charge.

"We were very concerned with him being a flight risk," Gansler said.