(Image credit: Iowacoldcases.org)

A man was renovating his home in Sac City, Iowa, when he came across what appeared to be skeletal remains in his basement. When he called the police, authorities arrived on scene and confirmed his suspicion.

"It was found buried in a very inaccessible spot in the basement," Sac City Chief of Police John Thomsen told ABCNews.com. "There are suspicious circumstances to it just for where the remains were found."

The remains were sent to the Iowa State Medical Examiner's Office for autopsy and possible identification, according to police. Dental records positively identified the remains as those of Mark Koster.

Koster, 58, went missing on July 4, 2009. His disappearance was investigated at the time and a search warrant served on his home turned up no signs of foul play. He was legally declared dead at his family's request in 2010, according to ABC News' Sioux City affiliate KCAU-TV.

He reportedly had an unidentified male roommate living with him for about three months before he disappeared, Thomsen said. Neighbors knew of the man, but do not know his name. The case is currently under investigation.