A federal grand jury returned a seven-count indictment late yesterday against Prescott W. Sigmund for allegedly trying to kill his father with a pipe bomb in July.

The indictment, filed in U.S. District Court in Washington, charges Sigmund, 35, with seven felonies, including assault with intent to kill while armed, interstate transportation of an explosive with intent to harm and malicious disfigurement. The maximum penalties for all charges total more than 100 years in prison.

Sigmund, of Potomac, is being held without bond in the D.C. jail, where he was taken after his surrender last month in Missoula, Mont. Police and prosecutors said that after Sigmund saw himself on the Fox television show "America's Most Wanted," he drove to the local police station and turned himself in, ending nearly four months as a fugitive.

According to court documents filed by prosecutors, Sigmund told authorities, "I tried to kill my father," when he arrived at the police station.

After extradition to the District, Sigmund entered a not guilty plea to all charges during his initial court appearance in federal court nearly three weeks ago.

His attorney, David Bos, could not be reached for comment last night.

The indictment, which had been expected, is the latest development in a bizarre string of events that began July 12, when Wright Sigmund, 21, Prescott's half brother, got into his father's Chevrolet Blazer to run errands. The vehicle was rigged with a pipe bomb. The resulting explosion critically injured Wright Sigmund, ripped the vehicle apart and rocked the parking garage on Wisconsin Avenue in Northwest Washington.

Prescott Sigmund disappeared three days later. He abandoned his 1990 BMW 325i at the Fairfax-Vienna Metro station, leaving a note to his wife that requested cremation when his body was found.

"I am sorry for the actions I am about to undertake and hope that someday you will be able to forgive me. I do this not because I had any involvement with Wright and Dad, but I know that this investigation will unravel the lie that my life has been for so long."

Sigmund was not seen again until he turned himself in. He had apparently taken a bus to Missoula, changed his name and taken a job at a local hotel, prosecutors said in motions filed at his detention hearing.

Police have said that Prescott Sigmund had been having financial difficulties and may have hoped to benefit from the death of his father, an insurance executive. The indictment provides no details about a possible motive.

Channing Phillips, spokesman for the U.S. attorney's office, said last night that Sigmund's arraignment had not been scheduled. He declined further comment.