Investigators probing the death of a federal prosecutor from Baltimore whose battered body was found repeatedly stabbed and dumped in a Pennsylvania creek suspect the killing was the result of a personal relationship that turned violent and was not linked to his work, a law enforcement official said yesterday.

Authorities were expected to work through the weekend assembling evidence in the grim mystery of how Jonathan P. Luna, 38, wound up dead in rural Pennsylvania shortly before dawn Thursday.

He had gone to the federal courthouse in downtown Baltimore late the night before to complete some paperwork for a plea agreement.

But the official, who spoke on the condition of anonymity, said authorities could announce as early as Monday that the slaying was unconnected to Luna's job and was expected to be handled as a state murder case by the local prosecutor in Lancaster County, Pa. - not as a case of federal kidnapping or the killing of a federal law enforcement officer.

Two other sources close to the investigation said yesterday that authorities had largely discounted any link between Luna's slaying and the defendants in the drug conspiracy trial where he was serving as the lead prosecutor this week in U.S. District Court in Baltimore.

The defendants in that case - a Baltimore would-be rap artist and his one-time business associate - pleaded guilty Thursday morning to distributing heroin from the Hampden studio of their upstart music label, Stash House Records.

Luna, a married father of two young boys, was reported missing when he failed to appear in court for that 9:30 a.m. hearing.

One of his last contacts was with a defense lawyer in the case, whom Luna told that he was returning to the federal courthouse late Wednesday evening to complete paperwork for the plea agreements.

Luna's father, Paul D. Luna, said yesterday that his son's wife has told him someone called Luna on his cell phone while he was at home about 11 p.m. Wednesday.

According to his father's account, Luna did not say who was on the phone, but told his wife: "Honey, I'm sorry, I have to go back to the office."

Building records indicate that Luna was inside the federal courthouse about 11:30 p.m. Wednesday, according to sources, who also said Luna had parked his car inside the building's tightly secured garage.

The silver Honda Accord was discovered about 5:30 the next morning, nose-down in a small creek near a well-drilling business in Brecknock Township, Pa.

Court records made public yesterday said there was blood in the car, along with cash scattered inside the vehicle. Luna's body was found lying facedown nearby.

A Pennsylvania coroner said yesterday that Luna died from drowning and suffered multiple stab wounds in the neck and chest - but, contradicting earlier reports, said Luna was not shot.

A federal law enforcement source said Luna was stabbed 36 times and some of the wounds were "defensive," indicating he had tried to fight off his attacker.

Among the clues Luna left behind in Baltimore were the most ordinary details: His cell phone and wire-rimmed eyeglasses were in his courthouse office, according to sources familiar with the investigation.

His bank ATM card, and a series of withdrawals on his account during the hours he was missing, also were being examined by investigators as they built a detailed timeline of what happened to Luna after he left the Baltimore courthouse.

When his body was discovered at dawn in Brecknock Township, Luna was dressed in a business suit, shirt and tie, an overcoat, socks and shoes, said Dr. Barry D. Walp, the Lancaster County coroner.

Walp said there were no wallet or cell phone in Luna's pockets, but he was wearing a work identification badge around his neck.