Investigators are focusing on Luna's personal life in the search for clues to the identity of his killer or killers. Officials said Luna had traveled several times in recent months to the area of Pennsylvania where his body was found, and authorities were not immediately aware of any work-related business that would have taken him to the region.
Investigators also were looking into a credit card Luna, 38, held without his wife's knowledge, and into postings of messages by someone who went by the name of Jonathan Luna in Web sites where people advertise for female sex partners, according to a federal law enforcement official.
The Sun newspaper of Baltimore reported that the author of the messages, from April 1997, described himself as a discreet 31-year-old married, professional black male seeking a white female sexual partner.
The body of the Baltimore-based prosecutor was found Thursday, stabbed 36 times and left face down in a creek in rural Brecknock Township, Pa., about 80 miles west of Philadelphia.
A law enforcement source told the Sun that Luna had been severely beaten in the area of his genitals, suggesting a "highly personal" motive for the slaying.
A source close to the case also told the newspaper that Luna's body was positioned directly in front of his car, suggesting that his killer or killers may have considered running him over.
In a related development, electronic records show Luna's car headed toward the Philadelphia area on a roundabout route leading to the spot where his body was found.
A federal law enforcement official said Luna's car passed through automated EZ Pass toll booths on highways leading northeast toward the Philadelphia area. The source said Luna also made a cash withdrawal along the way and appears to have bought gas outside Philadelphia with a credit card.
Luna left his office at U.S. District Court in Baltimore about 11:30 p.m. Wednesday, according to courthouse records. His body was found the next morning.
He had been due in court Thursday to complete a plea bargain involving a violent heroin ring. Investigators said they have found nothing to indicate the crime was connected to his work.
Investigators planned to meet Monday in Baltimore, and also planned to release an estimated outline of Luna's journey and a photo of the silver 2003 Honda Accord the assistant U.S. attorney was driving.
"We're going to try provide some kind of general information of a timeline and ask the public if they have seen him at a certain place at a certain time," said Vickie LeDuc, a spokeswoman for U.S. Attorney Thomas DiBiagio.
FBI agents visited a Mobil station at a rest stop on Interstate 95 in Newark, Del., between Baltimore and Philadelphia, said Ann Cochran, the station manager. She said agents asked if any employees had seen Luna, but she did not know whether they had.
Investigators also were in Lancaster County, Pa., during the weekend, showing hotel owners pictures of Luna. Hotel owners and managers said they were asked to review their guest registers for Wednesday and Thursday nights and asked if they had video security cameras.
Luna had traveled to Lancaster County several times in recent months, and authorities were not immediately aware of any work-related business that would have taken him to the region.
While a federal law enforcement source told the Associated Press that investigators had found nothing to indicate the killing was related to Luna's work, Luna's father and friends are convinced his death was tied to his career.
Luna's father, Paul D. Luna, said authorities asked him about his son's personal life, including his finances, relationships and trips he made in the last month.
Paul Luna, 83, said he had urged his son to return to private practice instead of prosecuting drug dealers and violent criminals. The assistant U.S. attorney had just worked out plea deals in one drug case late Wednesday.
"I was warning him many times," Paul Luna told the AP on Sunday. "I'm very positive that this is for his work. I even told that to the FBI."
He said he didn't think his son was having any financial problems, and had no knowledge of any possible extramarital affair. His son appeared to be happily married to his wife, Angela, he said.