It was easy to assume that most of the 18 men found dead within an hour's drive of this bayou town of oil, shrimp and sugar workers had simply placed themselves in harm's way, plunging into a subculture of illegal drugs.

But Police Chief Patrick Boudreaux was troubled by clues that set several cases apart from the typical drug-related killings in southern Louisiana, where victims are often shot and left to die.

These victims, many of them poor and some willing to prostitute themselves for drugs, had been strangled, possibly by someone they knew and trusted. There were no bruises or broken bones.

"If you're going to strangle me, we're going to fight," police spokesman Lt. Todd Duplantis said as he tried to explain the odd nature of the killings. "And I'm sure there'd be some kind of signs of me fighting you."

Three victims were found in the same sugar cane field. Some were missing their shoes, a detail that was "really weird" to Sherri Parr, who lives on a street of small houses and trailers where one of the victims, Leon Lirette, 22, also lived.

"They didn't have a lot of money . . . it wasn't like they were $300 shoes," Parr said. "It sounds more like it would be a trophy. That's the thing that's kind of scary."

Authorities now say the 18 deaths since the late 1990s could be linked to what is possibly the third serial killer investigation in southeastern Louisiana in the past few years.

What they cannot say is whether the killer is working alone. They have yet to say publicly whether they are sure if the killer is a man or a woman. Some remain skeptical about whether the term "serial killer" is even appropriate and whether Boudreaux unnecessarily frightened residents by uttering the words in recent public statements.

Boudreaux hasn't wavered.

"Although direct evidence to link the homicides together may not be there, there are enough correlates in the manner -- method of death, type of victim and the disposal locations -- to indicate . . . it would be prudent to warn that there may be linked homicides of a similar offender, which is the definition of a serial killer," Boudreaux said.

Coming up with hard evidence has been the hard part.

There has been nothing so solid as the DNA evidence that led to the arrest of Derrick Todd Lee in the rapes and killings of several women, some of them college students, in the Baton Rouge area. Lee was convicted last year in two killings.

The second serial killer case resulted from a combination of DNA evidence and reported confessions by Sean Vincent Gillis in the deaths of eight women. He is scheduled for trial in October.

In the latest case, authorities arrested two people of interest over a month ago on charges unrelated to the deaths, only to have yet another victim turn up this month.

Investigators in Lafourche Parish -- which borders Terrebonne Parish, where Houma is located -- made the two arrests while searching a home. One of the men was released soon after. The other, Johnny Billiot, was once a roommate of one victim and was charged with possession of child pornography. He remained in jail when Alonzo Keith Hogan, 34, who had last been seen riding his bicycle in Houma, was found strangled in neighboring St. Charles Parish, where his body apparently had been dumped.

Although Lafourche Parish authorities are participating in the multi-agency investigation into the deaths, they remain critical of Boudreaux's use of "serial killer."

"We're taking these one at a time," said Lafourche Parish sheriff's spokesman Larry Weidel. "Some have similarities, some don't. It's all speculation until it's proved that these can all be put together. It's a lot of cases to be linked to one or two individuals."

In any event, the FBI is offering help from experts in behavioral sciences, as well as crime-scene specialists who use material compiled nationwide to match scenes to known suspects.

Louisiana Attorney General Charles C. Foti Jr. also set up a clearinghouse to share information among offices working on the related cases.

Foti is among those who refrained from using the term "serial killer," but his spokeswoman, Kris Wartelle, said that's "kind of beside the point because most people are calling it that."

"Do we think there is a connection? Possibly," Wartelle said. "And that's the way it's being investigated for now."

Maj. Sam Zinna of the St. Charles Parish sheriff's office said the 18 possibly linked deaths can be broken into two groups. Nine unsolved cases from the late 1990s and nine since 2000. The more recent group has more similarities, in that many of the victims had ties to the Houma area and were strangled. But Zinna said it makes sense to include the other cases in the hope of solving some of them.

Because most victims led what authorities termed "high-risk" lifestyles, there has been little hysteria among the public. But in Houma, the apparent epicenter of the investigation, residents have become disillusioned with where they live and more aware of their surroundings.

Parr said that she and her neighbors take note of every car or person they do not recognize, and that her 16- and 17-year-old sons stopped going to the store by themselves at night.

Arthur Eschete said a number of the customers who visit his seafood store bring up the investigation and "are real upset about it."

"It's not just because of the serial killer. The streets are just not as safe as they used to be," Eschete said.

Surrounded by wetlands and sugar cane fields about 60 miles southwest of New Orleans, this city of 32,000 is laced with canals and dotted with corrugated metal buildings housing businesses related to work or play at sea. It has always been working-class, with people hardened by the physical demands of working on offshore rigs and shrimp trawlers and in the cane fields.

Although crime has increased in recent decades, the latest investigation seems to have driven home that Houma is no longer a place spared the frightening violent crimes that occur in New Orleans or are seen on television.

When Eschete, 60, was a teenager in Houma, crime rarely surpassed the level of drag races when the canal bridges were up and the nearest patrol car was on the other side. But since this spring, TV news trucks have been seen speeding toward Houma for interviews with authorities about the latest body found.

"We hear about things happening in New Orleans and other cities around the country and tend to think, 'Not in our town,' " Eschete said. "But when stuff like the serial killer shows up, we go, 'Oh, man, what's happening now?' "

In April, Kurt Cunningham became one of the 18 men killed near Houma, La., in the past few years. Some say a serial killer is responsible; others disagree.