MACOMB TOWNSHIP, Mich. – Federal, state and local officials are working to dig for clues in Macomb Township this week in a search to crack decades old cold cases.

Local police, along with help from the FBI, began excavation on Monday, May 7, along the North Branch Clinton River near 23 Mile Road and North Avenue.

It's the same field where 13-year-old Cindy Zarzycki's remains were found after her killer led investigators to the spot in 2008. Arthur Ream killed Zarzycki when she was just 13 years old in 1986.

The disappearance of Kimberly King, from Warren, in 1979, might have connections to convicted killer Arthur Ream. King was 12 years old when she vanished.

On Wednesday, during day three of the dig, police provided their first official update to media, saying they haven't found remains yet, but are confident the site is indeed a grave yard.

Police also confirmed that Arthur Ream is the main suspect. Dwyer said Ream bragged to other inmates about killing 4-6 other girls and then ended up failing a polygraph test when questioned by detectives.

"Based on our information, we believe he chose to bury these other teen girls in the same general area," Dwyer said. "I would describe Ream as a serial rapist and killer."

Officials say they have found “something” indicating that 4-6 girls could be buried at this site, but they have not yet found remains. They describe it as “finding a needle in a haystack” @Local4News — Koco (@KocoMcAboy) May 9, 2018

Who is Arthur Ream?

Ream is a convicted murderer currently in prison for the rest of his life.

In 1975, Ream was charged with taking indecent liberties with a child and sentenced to five years in prison, according to Michigan Department of Corrections records. In 1996, he pleaded guilty to third-degree criminal sexual conduct with a minor between 13 and 15 years old, the records show.

A judge handed down a 15-year sentence, which Ream was serving when he was implicated in Cindy Zarzycki's murder.

Ream didn't know Local 4's cameras were rolling in 2008 when he spoke to investigators and described the property at 23 Mile Road and North Avenue where he buried 13-year-old Zarzycki after he murdered her in 1986. Watch the video below:

He is serving a life sentence at Michigan's Earnest C. Brooks Correctional Facility in Muskegon Heights.

These are the cold cases that may be connected to Ream:

The case of 12-year-old Kimberly King, from Warren, who disappeared in 1979

The disappearance of Kellie Brownlee, from Novi, when she was 17 in 1982

The case of Kim Larrow, who disappeared from Canton Township in 1981, when she was 15

The case of Nadine O'Dell , from Inkster, when she was 16 in 1974

The disappearance of Cynthia Coon, from Washtenaw County, when she was 13 in 1970

Kimberly King, Kellie Brownlee and Kim Larrow

Police sources told Local 4 they are positive Ream is responsible for other crimes, but they aren't certain he's responsible for the disappearances of these girls.

The case of Nadine O'Dell

Brenda Lee Handloser was only 9 when her older sister Nadine disappeared.

More than 40 years later, she remains committed to seeing her sister's case solved.

"I know there is somebody out there that knows, you hear it all the time you know, somebody has seen something and I know somebody had to see something it was during the day," Handloser said.

According to NamUs, the National Missing and Unidentified Persons System, Nadine Jean O'Dell was last seen on Aug. 16, 1974. The time was shortly before 9:30 a.m. and she was walking down John Daly Road toward Michigan Avenue in Inkster.

O'Dell was 16 years old at the time and was heading to Taylor to babysit at her boyfriend's younger siblings. Handloser said Nadine's boyfriend would meet her at the halfway point.

"She didn't make it to that point," Handloser said. "He came to the house and he was like 'Where's Nadine?' She wasn't there and that is how it all started."

Handloser said Nadine was the second oldest child in her family.

"I just remember her as a very quiet person. She played with us and she babysat a lot," Handloser said.

If she is still alive, O'Dell would be about 59 years old.

Read more here.