Suspected serial killer arrested after 14 years: 'We're pretty sure he would've killed again'

A man charged with a Florida woman's murder has been linked through genetic genealogy to the killing of three women from over a decade ago -- leading authorities to believe a serial killer is now "off the streets."

"Had we not done this [arrest], we're pretty sure he would've killed again," Palm Beach County Sheriff Ric Bradshaw told reporters Monday.

Robert Hayes, 37, was arrested Sunday and charged with one murder, and remains a suspect in three others from 14 years ago, authorities said.

The case began in 2005 and 2006, when three women -- Laquetta Gunther, Julie Green and Iwana Patton -- were fatally shot in the head in separate incidents, said Daytona Beach Police Chief Craig Capri.

"All three were discovered naked and face down on the ground, with their clothes either under them or found nearby," police said in a statement.

Gunther was killed on Dec. 26, 2005; Green was killed less than a month later, on Jan. 14; and Patton just a few weeks after that, on Feb. 24, 2006.

The three cases were considered linked: two of the three victims were linked by forensic evidence, while two of the three were linked by DNA, Capri said.

Years went by without a lead in any of the killings.

Then on March 7, 2016, about 200 miles south of Daytona Beach, Rachael Bey, a 35-year-old prostitute, was found naked, severely beaten and strangled to death along a highway in Palm Beach County, according to the probable cause affidavit.

DNA of an unidentified man was recovered from Bey's body and entered into the law enforcement database CODIS (the Combined DNA Index System), said Palm Beach County Sheriff Capt. Mike Wallace.

The unknown male DNA from Bey's body matched the mystery suspect in Gunther and Green's killings, said Capri, and investigators in Daytona Beach and Palm Beach County began working together.

Though they had DNA matches, the suspect's name was not known. That's when investigators used genetic genealogy, which led to Sunday's arrest of Hayes, authorities said.

Genetic genealogy compares unknown DNA evidence to public genetic databases to identify suspects through their family members -- and has been called a "game-changer" in the effort to crack cold cases.

Since the arrest of the suspected "Golden State Killer" in April 2018, at least 70 suspects have been identified through the technology, according to CeCe Moore, the chief genealogist at Parabon NanoLabs, which investigated the Bey murder among others.

Moore has appeared as an expert in ABC News "20/20" episodes and has been quoted in ABCNews.com articles.

Authorities did not elaborate on which relatives of Hayes were found through genealogy, but on Friday, investigators zeroed in on him. They collected a cigarette he had discarded, according to the probable cause affidavit.

The sample was taken to a lab where officials found that the DNA from the cigarette matched the DNA from Bey's killing and from one of the Daytona Beach killings, according to the probable cause affidavit.

Palm Beach County investigators arrested Hayes on Sunday for the first-degree murder of Bey.

A separate killing of a woman, Stacey Gage, in January 2008 is being investigated to see if it's connected to the other four murders. There is no physical evidence, however, linking it to the other murders at this time, police said.

Hayes, meanwhile, has not been charged in any of the Daytona Beach cases, police said, but he is tied by DNA to Gunther and Green's slayings and is linked by forensic evidence to Patton's death.

He lived in the areas where Bey and the three Dayton Beach victims were last seen, according to the probable cause affidavit. It's believed he attended Bethune-Cookman University in Daytona Beach, Capri said.

It is not clear how the victims and the suspect allegedly came into contact, authorities said. The victims seemed to be targeted randomly, Wallace said.

Hayes' criminal history only involves traffic-related offenses, Capri said.

Hayes made his first court appearance Monday morning and was held on no bond, authorities said. His public defender did not immediately respond to ABC News' request for comment.

Bey's brothers traveled from out of state to attend Monday's press conference in Palm Beach County. Her family chose not to speak.

The State Attorney for Palm Beach County, Dave Aronberg, vowed to get "justice" for Bey.

ABC News' Ben Stein contributed to this report.