Assistant U.S. Attorney Jonathan P. Luna, 38, was discovered face-down in the water behind the parking lot of a well-drilling company in Lancaster County, Pa., about 70 miles from Baltimore, Brecknock Township police said. A car was near the body, police said.
Investigators say Luna disappeared around midnight Wednesday just after receiving a telephone call at his Baltimore home, reports CBS News Correspondent Jim Stewart.
Several of the stab wounds were around Luna's throat, reports Stewart.
"Let there be no doubt. Let there be no doubt that everyone in law enforcement, local police, state police, the United States Marshals Service, ATF, FBI, are united," U.S. Attorney Thomas DiBiagio said. "We will find out who did this and we are dedicated to bringing the person responsible for this tragedy to justice."
Luna was prosecuting Baltimore rapper Deon Lionnel Smith, 32, and Walter Oriley Poindexter, 28, who were accused of dealing heroin and running a violent drug ring from their Stash House Records studio.
Authorities did not say whether the two men are under suspicion in the slaying. They were behind bars at the time.
Luna and the defense attorneys negotiated through the afternoon Wednesday and reached a plea bargain on the drug charges at the end of the day, said U.S. District Judge William D. Quarles Jr., who presided over the case. The men entered their guilty pleas around noon Thursday.
Smith pleaded guilty to distribution of heroin and possession of a weapon for the purposes of drug trafficking. Poindexter pleaded guilty to distribution of heroin to a government witness.
Luna was supposed to be in court Thursday when they entered their pleas, but he failed to show and the FBI began looking for him.
His body was found around daybreak not far from an exit on the Pennsylvania Turnpike. He had been repeatedly stabbed and shot.
Luna was married and had two children. He grew up in New York City, attended Fordham University and went on to law school at the University of North Carolina.
He was an attorney at the Federal Trade Commission from 1994 until 1997. He then worked as a prosecutor in Brooklyn before coming to Baltimore.
The judge described Luna as a "wonderful young man, responsible, charming and highly intelligent. He had genuine trial skills as a lawyer and juries loved him."
Attorney General John Ashcroft called it a "tragic death."
"I express our deepest condolences to Jonathan's family, colleagues and friends," Ashcroft said. "We share his family's grief and will provide any support and assistance to help them through this difficult time."
Smith's attorney, Kenneth Ravenell, called Luna a "a good friend."
"I was kind of his mentor in many ways," Ravenell said. "He'd call me often and discuss things outside of what we did on cases."
During opening statements in the trial, Ravenell urged jurors to separate what they have heard about rap music from the trial.
"I suspect that what a lot of you know about rap music is what you hear on the radio or see on the TV, and a lot of that's not good," he said. "But Mr. Smith isn't on trial for being part of the rap industry."
He said that as Smith tried to build a legitimate career in the music business, he made the mistake of failing to cut his ties with criminal associates from his past.
Smith recorded under the name Papi Jenkinz, but his recording business closed in the spring after the arrest.
The charges against Smith carry up to 25 years in prison, and those against Poindexter carry up to 60 years.
Luna had also prosecuted cases against a man who videotaped a neighbor child as she slept in her home and against a man who plotted to burn down a home to force six Mexican men out of a neighborhood. Luna also tried three men involved in a violent crack distribution network in Baltimore. All the defendants entered guilty pleas.
Other federal prosecutors have been the target of violence in the past.
Federal prosecutor Thomas C. Wales was shot to death in Seattle three years ago in an unsolved murder. The search for the killer has focused on at least one of the cases he had prosecuted.
Federal prosecutor Larry Barcella, now in private practice, was the target of a thwarted murder-for-hire scheme by ex-CIA agent Edwin Wilson, whom Barcella had put behind bars for selling weapons and explosives to Libya.