Published: Aug 04, 2010 4:10 PM EDT
Updated: Aug 04, 2010 1:10 PM EDT

YUMA, Ariz. (AP) -Yuma authorities have charged a man imprisoned in Florida in the slaying of a Dateline man 22 years ago.

The Yuma County Attorney's Office has issued a felony complaint for 53-year-old Michael McIlrath in the 1988 murder of Efren Contreras-Portillo.

McIlrath currently is serving a prison sentence in Florida's Pasco County for sexual battery on a child under the age of 12. Yuma County Attorney Jon Smith says McIlrath will be extradited back to Yuma for prosecution.

Authorities say the body of the 29-year-old Contreras-Portillo was discovered in a field and inside a sealed 55-gallon oil drum on Feb. 24, 1988.

Investigators say McIlrath worked with Contreras-Portillo at a cotton gin that was in operation in the Dateline area in 1998. They say McIlrath left Arizona shortly after the murder, but he recently contacted Yuma authorities from prison and wanted to clear his conscience about the Contreras-Portillo case.