It doesn’t say anything in the article about why he decided to plead guilty.
However, if I had to venture a guess, I’d say that his attorney told him that the evidence against him was sure to get him convicted. So he pleads guilty and hopes to get a lessor sentence.
He’s going to be the “Belle of the Ball”.
“Under Peruvian law, a prison sentence for a “sincere confession” to a murder is normally much shorter than one for an outright guilty plea. He could spend less than a decade behind bars.”
http://www.msnbc.msn.com/id/45954171/ns/world_news-americas/