LAKE COUNTY -- No arrests have been made related to a homicide investigation that started as a three-year-old missing persons case, but Lake County's prosecutor said law enforcement officials are currently investigating possible persons of interest.

"There are persons of interest in the case, but a strategy has to be developed on how to proceed with the case," Prosecutor Craig Cooper said.

The remains of Richard A. Ashbrook were discovered buried in the backyard of a Pleasant Plains Township residence in early June and identified by personnel with the Michigan State Police Crime Lab several days later.

Ashbrook was last seen in November 2017, and was reported missing by his family on Feb. 11, 2018, according to Det./Lt. Brad Nixon with the Lake County Sheriff's Office.

Sheriff Rich Martin said although Ashbrook's disappearance was originally being investigated as a missing person, the case is now considered a homicide.

However, he said previously police believe it was an isolated incident and there is no threat to the general public.

Cooper said he is still waiting to receive information from the sheriff's office before they can move forward with possible charges.

According to Martin, Ashbrook's remains were found at his last known residence, where he reportedly lived with a woman who he was believed to have been in a relationship with previously.

Cooper said police are expected to carry out some additional search warrants soon, but did not comment on which properties would be searched.

He explained although there is a great deal of investigation left to do in the case, he hopes to eventually provide closure to Ashbrook's family.

"This is such a sad situation," Cooper said. "The goal is to, over time, solidify what happened to Richard Ashbrook and I hope we can all do that. I hope in the end we can figure out what happened to him. It's going to take time to find the answers."

At the time he went missing, Ashbrook was 47 years old.