(CNN) Genetic genealogy led Florida investigators to a suspect in a 2016 killing, and he has been linked through DNA and other forensic evidence to at least three other slayings from a decade prior, authorities said Monday.

Even with that link, it was a cigarette butt that the suspect dropped at a bus station last week that led to his arrest, court documents indicate.

Robert Hayes, 37, was arrested Sunday without incident. A Palm Beach County judge ordered him held without bail Monday on a first-degree murder charge, pending a grand jury proceeding. Hayes, wearing a dark jail uniform, his wrists shackled at his waist, appeared alongside a public defender.

The county's Office of the Public Defender said it does not comment on pending cases.

"We will keep working every single day, every single hour until we find these monsters that are out here and do these things because I can guarantee you, folks, if we hadn't put this individual in jail, he would've done this again and we would've had another innocent victim out here," Palm Beach County Sheriff Ric Bradshaw told reporters.

Links to other killings

Though Hayes has been charged only with 32-year-old Rachel Bey's March 2016 strangulation death in Palm Beach County, Daytona Beach Police Chief Craig Capri said Hayes will be charged in at least three killings in that city: those of Laquetta Gunther, 45, in 2005; Julie Green, 34, in 2006; and Iwana Patton, 35, in 2006, all of whom were shot in the head.

Investigators will continue their investigations to determine if Hayes is a suspect in any other killings, including that of 30-year-old Stacey Gage in 2008, authorities said.

DNA from the 2016 killing matched evidence found in the 2005 slaying of Laquetta Gunther, police say.

DNA obtained in the Bey investigation matches DNA in the Gunther and Green probes, Capri said. Patton's body spent a long time in the woods after her killing, complicating efforts to collect DNA, the chief said, but ballistic evidence in her death -- namely, a casing from a .40-caliber firearm -- links hers to the other Daytona Beach killings.

Calling Hayes a "disgusting serial killer," Capri said the delay in charging Hayes in the other three killings stems from his department's desire to build a "solid, solid case" against him and to ensure he never gets out of prison.

"I can't be more happy today that we got this killer off the street so nobody else can become a victim, and now we're going to tie some loose ends up and then move forward with going after this guy and prosecuting him for these three murders," he said.

More charges coming

There is no rush to file the Daytona Beach charges because Hayes is in jail and isn't a threat to the public, State Attorney R.J. Larizza said. It was too early to say whether his office will pursue the death penalty, he said.

"We're going to be right when we ultimately make the charging decision in these cases," the prosecutor said.

Police have informed the families of Hayes' arrest. Volusia County Sheriff Michael Chitwood, who was Daytona Beach's police chief at the time of the killings, says he personally spoke with one victim's family.

Police Lt. Steven Beres walks by the alley where Laquetta Gunther's body was found in 2005.

"They are obviously ecstatic. They didn't think they'd be alive to see this day come," he said.

Hayes has only a minor criminal history, involving traffic violations, Capri said. A student at Bethune-Cookman University at the time of the Daytona Beach killings, Hayes was questioned by law enforcement because of a firearm purchase he had made, the chief said. It was one of hundreds of interviews that law enforcement conducted in the case, he said.

"Hayes purchased the firearm at the beginning of December 2005, with one of the murders then occurring December 26, 2005," a probable cause affidavit says. "He provided statements in March of 2006, that he had given the firearm to his mother, who lived in West Palm Beach. However, Hayes also reported a (40) caliber firearm as being stolen from his vehicle in Riviera Beach, Florida, in December 2006."

The suspect lived in the Daytona Beach area during the Daytona Beach killings, and he lived in West Palm Beach during the slaying that occurred there, police said.

The cigarette butt

Authorities said they got a major break in the case using genetic genealogy, which is a combination of traditional DNA evidence with the type of genealogical analysis made famous by companies like 23andMe and Ancestry.

It was the DNA of one of Hayes' relatives, found in a genetic geneaology database, that led investigators to Hayes, said Lori Napolitano, chief of the Florida Department of Law Enforcement's genetic genealogy investigations. She did not provide other details, except to say that the more DNA two people share, the more closely they are related.

Daytona Beach police investigate the Iwana Patton crime scene in February 2006.

Following the death of Bey, whose battered body was discovered by road crews along State Route 710, police obtained DNA from a sexual assault kit and put it into a law enforcement database, where they got hits on the three Daytona Beach murders, Palm Beach County Sheriff's Capt. Mike Wallace said.

On Friday, investigators following Hayes obtained his DNA from a cigarette butt he discarded at a bus stop, according to the probable cause affidavit. The DNA from Bey's sexual assault kit was a better match for Bey and Hayes than it was for Bey and any other person on the planet, Wallace said.

"So we have our guy," he said.

Though authorities believe Hayes selected his victims at random, he had met Bey earlier on the evening of March 7, 2016, the day she was killed, Wallace said.