PHOENIX (AP) -- A man accused of watching his teenage friend kill a woman last year and helping him conceal the body has pleaded guilty to hindering prosecution.Maricopa County prosecutors say 18-year-old Christian Blakely entered into a plea deal Friday and will serve supervised probation. He may also get jail time when he's sentenced at a later date.Blakely has been in custody since October 2013 on suspicion of first-degree murder, conspiracy to commit first-degree murder, tampering with evidence and concealing a body.Prosecutors say Blakely was released Friday on electronic monitoring. He's agreed to testify against his friend, who's a Mesa juvenile accused of killing his mother.Authorities believe the 36-year-old woman was choked and struck with a frying pan and hammer. Her body was later found in a backyard shed.© 2014 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.