OKLAHOMA CITY, Oklahoma (CNN) -- A string of unsolved slayings across six states has prompted dozens of state investigators to consider whether a serial killer is responsible for the deaths of at least seven women.

Investigators from Oklahoma, Texas, Arkansas, Louisiana, Tennessee and Mississippi will meet Friday at Oklahoma State Bureau of Investigation headquarters to compare notes on at least seven murder cases -- possibly as many as 10.

The murders date back over the past two years. The victims range in age from 19 to 47.

The female victims had a striking number of similarities:

• Most had a history of prostitution or were known prostitutes.

• Most were last seen at truck stops along Interstate 40 in Oklahoma.

• Most of the victims' bodies were found naked, with no other belongings in the area.

• Most of the victims' bodies were found dumped along highways.

• Some were sexually assaulted.

"We have entertained the idea we may be talking about a serial killer," said Jessica Brown, spokeswoman for the Oklahoma State Bureau of Investigation. "But we have nothing at this point in time that directly links these homicides to one person.

"We believe there's enough information about the different homicides that we are considering the possibility that they could be connected," she said.

The FBI has helped law enforcement agencies with case interviews and also has provided profiles of potential suspects, an FBI official said.

The most recent case involves Casey Jo Pipestem, a 19-year-old Native American woman from the Seminole tribe, who was last seen at a truck stop in Oklahoma City.

Her body was found January 31 in Grapevine, northwest of Dallas, Texas, dumped off an interstate bridge and into a creek. Her family said she was sexually assaulted. They worry that people will not care about these murder cases because the women tended to be prostitutes and on the fringe of society.

"I think if people looked at their background they would realize they were human beings, people with families," said Ted Underwood, Pipestem's uncle.

"If this individual has killed Casey and possibly nine others and is still out there, there's something wrong with this individual," he said. "He's an evil person, a sinister person who has no feeling for human life and will do it again. I just hope that law enforcement are putting in enough effort, manpower and resources to find this individual because he's going to bring a lot of grief to a lot of people and he's not going to stop until they catch him."

One of the more bizarre cases involves the body of a woman found last October in Gray County, Texas, in the Panhandle just east of Amarillo.

Authorities have been unable to identify the victim. She is believed to be in her late 30s, but no one has reported her missing.

Early on the morning of October 16, 2003, the woman was seen on a surveillance camera video at a Flying J truck stop in Sayer, Oklahoma, about 85 miles east of Gray County on I-40.

According to Gray County Sheriff's Chief Deputy Kelly Rushing, "The last thing she said to anyone is 'I've got a ride and I've got to go.'"

Two truck stop employees she was talking to said they do not know who she left with and there was no surveillance video of the area to provide clues.

About six hours later, the woman's naked body was found dumped along a barren, remote stretch of I-40.

One of the country's most prolific serial killers, Gary Ridgway, confessed to targeting prostitutes "because I thought I could kill as many as I wanted without getting caught."

Ridgway, known as the Green River Killer, eluded authorities for years before he was sentenced to life in prison in December 2003 for killing 48 women.

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How do you stop this type of killing if the victim willingly goes with the killer?....

Unfortunately lots of serial killers pick prostitutes for that very reason - not b/c they are prostitutes, but b/c they typically will go with anybody. They make for a limitless, and b/c of laws basically defenseless, pool of prey.