Last Updated May 9, 2018 3:15 PM EDT
DETROIT -- Authorities resumed digging in a Michigan forest Wednesdaywho have been missing for decades. Police announced their main suspect, a convicted murderer, had "bragged" about killing and failed a polygraph test.
The FBI and other agencies restarted the work at a site about 30 miles northeast of downtown Detroit in Macomb Township, police said. Authorities said statements by Arthur Ream to investigators and other inmates made them confident they would uncover remains at the 24-acre plot.
In 2008, Ream led police to the body of 13-year-old Cindy Zarzycki in the same wooded area, buried in a shallow grave. She was last seen in 1986 after being lured to a Dairy Queen in Eastpointe, just north of Detroit.
Ream was convicted of first-degree murder in her slaying. After his conviction, he told investigators that Zarzycki's body was buried near a creek. He also drew a map of the site and spent about an hour at the search scene with authorities before being returned to prison.
Crews arrived there again Monday, and began digging in earnest Tuesday, for the remains of Kimberly King, a 12-year-old girl who was last seen in 1979 in Warren.
Warren Police Commissioner Bill Dwyer told reporters Wednesday that "the suspect in this case also did brag about murdering four to six people to inmates where he is being housed."
Dwyer said that based on Ream's statements, authorities zeroed in again on the site several months ago as the possible location of more remains, but said they were waiting for the ground to thaw to begin the search.
Officials said Ream hasn't been cooperative and crews were meticulously going through the large plot of land. Dwyer said they haven't yet uncovered remains, but they have found iitems that make them believe they are searching the right area. He wouldn't detail what investigators have found so far.
"We do have, as you know, probable cause to believe this is a gravesite, no question about it," Dwyer said. "Kimberly King and other young female victims who were murdered are buried here."
Officials haven't publicly identified all of the victims they believe may be buried there, but Dwyer confirmed Wednesday 17-year-old Kellie Brownlee, who vanished from a Novi mall in 1982, and 15-year-old Kim Larrow, who disappeared from Canton Township in 1981, may be among them.
He said their disappearances fit with Ream's alleged "MO" of picking up hitchhikers. Before Ream's conviction in Zarzycki's death, he spent time in prison for the 1974 sex assault of a 15-year-old hitchhiker, he said.
Dwyer said Ream isn't believed to have known any of the victims they are searching for. Ream did know Zarzycki, who had been dating Ream's son at the time of her disappearance. Authorities said Ream, now 68, tricked her by telling her that he was planning a surprise party for his son.
King's sister, Konnie Beyma, spoke at the press conference, saying she has hope her sister's remains will be found and that the developments in the case bring hope to the families of other missing girls as well.
"It would mean a great deal to be able to bring her remains home," Beyma said.
Ream hasn't been charged in relation to King's case or the other missing girls.