Joseph Blackmer in a 2001 booking photo from the Elkhart County Sheriff's Department, Indiana.
GRAND RAPIDS (WZZM) -- Deputies say a man in prison has admitted to the 1981 rape of a woman in Byron Township.
Detectives say Joseph Blackmer, 54, is their suspect in the December 1981 sexual assault of a woman.
Investigators say that a 23-year-old woman living in the 7100 block of Houndstooth Street SW in Byron Township was sexually assaulted when a man in his late teens pushed his way into her home.
The woman was treated at a local hospital and a sexual assault kit on the case was submitted to the state crime lab. The case was closed in 1982 due to a lack of suspects and leads, but the evidence was retained.
A recent DNA test from samples found in the rape kit taken immediately after the 1981 assault were linked to Blackmer, who was in a nationwide DNA database.
Blackmer is currently in an Indiana prison, serving a 90-year sentence for a 1982 sexual assault in Elkhart, Ind. Kent County detectives travelled to his prison, where Blackmer admitted to his role in the 1981 rape.
Deputies were able to tell the victim about the DNA evidence, and Blackmer's admission to the crime.
"A horrific crime like this, certainly you can imagine the relief to know that the perpetrator has been found, that has probably been in prison for a long time as well and that there will be justice done in this case," says Undersheriff Jon Hess.
Prosecutors have authorized an arrest warrant for Blackmer on the 1981 crime.
Hess says cold cases like this one are reviewed on a regular basis.