TRENTON, N.J. (CBSNewYork/AP) — A New Jersey man who pleaded guilty to killing his mistress was sentenced to 25 years in prison Wednesday.

Rosario DiGirolamo must serve 85 percent of his term before he’ll be eligible for parole. He admitted killing 27-year-old Amy Giordano of Hightstown in June 2007 and dumping her dismembered body in a New York pond.

Judge Edward Neafsey called the crime “ghastly.”

DiGirolamo’s lawyers said a Google search for murder methods was a key factor in their client’s decision to plead guilty last month.

Evidence showed DiGirolamo had searched the phrase “lethal karate blows to the back of the head” days before the killing.

Defense attorney Jerome Ballarotto said the search evidence was “catastrophic.”

DiGirolamo left the couple’s 11-month-old son in the parking lot of a Delaware hospital.

(TM and Copyright 2011 CBS Radio Inc. and its relevant subsidiaries. CBS RADIO and EYE Logo TM and Copyright 2011 CBS Broadcasting Inc. Used under license. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed. The Associated Press contributed to this report.)

Watch & Listen LIVE