This undated photo provided by the North Carolina Department of Corrections shows John Boyer. Boyer has pleaded guilty to killing a woman in North Carolina and faces murder charges in slayings in Tennessee and South Carolina. (AP Photo/N.C. Department of Corrections)

EMERY P. DALESIO, Associated Press

JEFFREY COLLINS, Associated Press

COLUMBIA, S.C. - Long-haul trucker John Boyer's gray beard and round face give him a grandfatherly appearance, but when he opens his mouth, he seethes with anger toward women. This hatred had murderous results, authorities said, as he picked up prostitutes around the Southeast, killed them and dumped their bodies near interstate highways. He's accused of at least three slayings and is suspected in a fourth.

Boyer has pleaded guilty to killing a woman in North Carolina. He faces murder charges in slayings in Tennessee and South Carolina and authorities said he confessed to both of those crimes. The similarities of the cases and the apparent lack of remorse from Boyer have investigators encouraging their counterparts along highways around the Southeast to review unsolved killings and missing person files. Even his own attorney in the North Carolina case felt uneasy around him and wondered what else he might have done.

"I think there are a lot more. There's no telling. This guy traveled all over the country. Hopefully we'll get more of these cases solved through DNA," said detective Scott Smith of the Hickman County, Tenn., sheriff's office.

In the case Smith investigated, Boyer picked up 25-year-old prostitute Jennifer Smith in April 2005 and brought her to an abandoned parking lot just off Interstate 40. The two argued over money, and Boyer strangled the victim with the seat belt of his truck, dumped her body from the cab, and drove off, the detective said.

Her body was found in 2005 by a highway worker, but it took two years for investigators to match DNA found on her body to a sample Boyer gave after pleading guilty in North Carolina. Boyer confessed to the killing after investigators cornered him with the evidence, but he also went on a tirade against women, said Smith, who's not related to the victim.

The investigator was chilled by the hatred toward women from a man who had never been married and lived with his mother near Augusta, Ga. A woman who answered the phone Friday at a listing for Boyer's mother denied knowing him.

Darlington County, S.C., Sheriff's Capt. Andy Locklair immediately got the same impression when he stepped into an interview room to question Boyer about a killing in that state. The first thing Boyer said to him was: "What b---- are you here about?"

Locklair confronted Boyer earlier this month about the death of 34-year-old Michelle Haggadone. Her body was found in April 2000 beneath pine straw at a parking area on Interstate 20 near Florence, about 30 miles from the truck stop where Boyer had picked her up.

Boyer immediately denied killing Haggadone, lashing out at Locklair and an investigator with him.

"He said he had slept with a lot of prostitutes and a lot of them were detectives' daughters or prosecutors' daughters," Locklair said. "He just tried to get the upper hand from the start."

The captain added: "I'm not a behavior science expert, but he has some deep, deep issues with women."

Haggadone was strangled with a wire or cord after the two argued over the price of her services, authorities said. Her body went unidentified for a decade, until a DNA sample from a relatives matched a sample from her body.

Investigators had no DNA evidence to go on, but Locklair and another investigator realized several aspects of the crime, like what the victim was doing and where and how she was killed, matched the earlier slayings linked to Boyer. Without physical evidence to back him into a corner, Locklair decided he would try to draw a confession by gaining Boyer's trust. He told Boyer about his father, who also was a truck driver, then started trapping him in his lies.

Locklair's case and the one in Tennessee will take some time to resolve. Boyer will be taken to Tennessee to face a first-degree murder charge after his North Carolina sentence ends. He is going to face a murder charge in South Carolina, but Locklair isn't sure when he might end up in court because of the other two cases.

Boyer is serving a sentence of up to 12 years in a North Carolina prison after pleading guilty in 2007 to second-degree murder for killing Scarlett Wood in Wilmington four years earlier. Boyer said he was doing drugs with the 31-year-old prostitute when they had an argument, he pushed her, and she struck her head on furniture, authorities said. But an autopsy found Wood suffered broken ribs and facial bones, and her pelvic bones showed signs of a stabbing.

Boyer had been interviewed when Wood was still considered a missing person case because the two had been seen together at a party the night she disappeared. Authorities said detectives later got incriminating statements from Boyer when the case became a homicide investigation.

Boyer's attorney in the North Carolina case said he felt uneasy around his client.

"It wouldn't surprise me if there's other stuff out there," said H. Lawrence Shotwell. "I have absolutely nothing other than a gut instinct on that."

Boyer is a prime suspect in the death of 26-year-old Rose Marie Mallette, who was reported missing in 2001, said New Hanover County Sheriff's Det. Ken Murphy, a cold case investigator in Wilmington. The reported prostitute's remains were found wrapped in a blanket in an industrial area of the city a year later, the back of her skull crushed.

Boyer also seemed to target women who were especially small. For instance, Haggadone's family said she likely weighed less than 100 pounds when she was killed, while Boyer was 5-foot-7 and 293 pounds when he entered the North Carolina prison system in 2007.

Locklair said Boyer could be responsible for several more deaths because of his transient life as a trucker and his short temper when women disagree with him, a suspicion shared by a woman who searches for missing people.

Monica Caison, founder of Community United Effort Center for Missing Persons in Wilmington, said investigators need to look at three cases where women disappeared over five months in 1995 in Brunswick County, N.C., just west of Wilmington.

"We have a lot of unsolved missing persons in the general area where Mr. Boyer was known to frequent, live, and be. So, to me that alone warrants a second look," Caison said.

At least two of the unsolved cases involve woman who were small and slightly built, like Boyer's other alleged victims.

Cold case investigators in the area are aware of Caison's concerns and are checking their files for any links to Boyer.

Haggadone's family came back to South Carolina last week as authorities announced her identification and Boyer's confession. Her sister, Tuesday Miller, said she felt a cold presence when she went to the lonely parking area where she died.

"I am very overwhelmed. There are other people going through this same exact thing by this same exact guy," Miller said. "That's just sick. He's just evil."