Criminal profilers have said the slaying of Lisa Marie Kimmell appears to be the work of a serial killer, though that theory has yet to be proven.

In the 15 years since her homicide, experts close to the case have said the degree of criminal sophistication the killer displayed in disposing of Kimmell's body and in the removal of evidence -- such as ligatures -- raised that possibility.

Kimmell, 18, left Denver on March 25, 1988, in her black Honda CRX Si to drive to Cody. She never arrived.

Her body was found nine days later in the North Platte River off Wyoming Highway 220 about 25 miles south of Casper. The teen had been sexually assaulted, struck in the head and stabbed several times in the chest before her attacker threw her off Government Bridge.

A coroner's examination of Kimmell concluded that she "had suffered six separate stab wounds: Five of which were arranged in a circle in the chest of Lisa Kimmell with a sixth inflicted in the mid-upper abdomen." Each wound, the coroner said, could have been fatal, and each avoided striking a rib.

Another twist is that Kimmell's car was not recovered until 14 years after her slaying, when Natrona County sheriff's investigators unearthed it during a search of a Moneta property owned by 58-year-old Dale Wayne Eaton. Last month Eaton was charged with the first-degree murder, aggravated kidnapping and sexual assault of Kimmell.

Burial of the car but not the body baffles Robert Keppel, Ph.D, who led the investigation into serial killer Ted Bundy. Keppel has written several books on serial killings.

"Why did he even dump her over that bridge," Keppel wonders. "Why wouldn't he just bury her in the car?"

Greg Cooper, a former FBI profiler who investigated Kimmell's murder in association with a series of other murders from 1983 to 1997 in the Great Basin region of Nevada, Utah, Idaho and Wyoming, said last year that Kimmell was probably murdered by "a very organized serial killer."

But Keppel said his limited access to crime scene evidence in Kimmell's case makes it hard for him to say if the teen's homicide was the work of a serial killer.

From what he knows about the homicide, however, Keppel says he thinks Kimmell's killer displayed sophistication on a few levels.

"You can't generalize about a topic that's very difficult to generalize about. Serial killers are different," explained Keppel. "Some serial killers know their victim but the victim doesn't know the offender. Some serial killers know their victims and the victims know them."

FBI documents analyzing Kimmell's killing and profiling her slayer 10 years before authorities got a break in the case alluded often to the meticulousness of the killer.

An eight-page confidential analysis, prepared by FBI Supervisory Special Agent Ronald P. Walker at the FBI Academy in Quantico, Va., also lent itself to speculation that Kimmell's attacker was a serial killer.

Based on information given to the FBI by the Natrona County Sheriff's Office, the medical examiner's report and a victimology describing Kimmell's personality, Walker concluded that "it is significant that the assailant removed (a) ligature prior to disposing of the victim's body; this assailant is sufficiently sophisticated to realize the evidentiary value of such items."

"Lisa Marie Kimmell fell victim to an assailant who acted methodically and with purpose," the FBI reported. "She was a randomly selected victim whose path crossed with her assailant's by chance."

Walker's analysis -- written 10 years prior to the July 2002 unearthing of Kimmell's car on Eaton's Moneta property -- gives a chilling account of what her last days may have been like. It also suggests the possibility that more than one person was involved in her homicide.

Keppel, having examined Walker's analysis of the crime, said he realizes there may have been additional information leading the profiler to such a conclusion but he, nevertheless, tends to disagree with the theory of more than one killer.

"One of the things I disagree with in that profile is that the profiler kept referring to the possibility of a co-conspirator. I don't think that happened at all," Keppel said. "I think that's leading you down the wrong trail."

Walker, now a retired FBI consultant, was not available last week for an interview due to prior engagements, he said.

The property on which Kimmell's car was found is located just beyond the Fremont County border. Fremont County law enforcement officials who aided Natrona County in the search said recently that investigators in Fremont County are still in the process of revisiting unsolved case files for any possible connection to Eaton.

Keppel says investigators who suspect a person might be responsible for other murders are likely to begin piecing together a detailed timeline, or chronology, of the person's activities around the time each murder occurred. Information about every person who was associated with the alleged killer during those times would also be diligently explored.

"Trace his whereabouts and go back in time and try and place him near their crime scenes, because that is one avenue that you would have to pursue. And then you would pursue the avenue, too, that this may be his only victim," he explained.

Keppel said it's possible that Kimmell's killer was angry at a woman in his life around the time of the killing and that he just lashed out. It's likely that only similar circumstances would provoke the person to kill again, he added.

Typical serial killers are often portrayed as having a tendency to take souvenirs as proof of their deed. They clip news articles, take the victim's drivers licenses, or keep a lock of hair.

In Kimmell's case, investigators have yet to recover Kimmell's purse or driver's license, the clothes she was wearing when she left her job in Denver and a few pieces of her jewelry, court documents say.

Keppel said that in general, "some cases are obvious, because you find posing and sexual insertion of foreign objects and things like that, and you know that this guy has either killed before or he's gonna kill again."

But that's not always the case. Plus no one can really nail down what traits make one person more likely than another to become a serial killer.

It is suspected that Kimmell's abductor held her against her will for days after she disappeared, according to the confidential FBI report.

In his analysis, Cooper also said last year that he believed Kimmell's killer had killed before and had likely killed after.

He said the killer's abduction and sexual assault of Kimmell, the concealment of her vehicle and the "controlled and organized" knife wounds administered were consistent with an experienced killer.