A man accused of beating his grandmother with a golf club, stabbing her dozens of times and setting fire to the house they shared has been convicted of murder in Maine.

A jury returned the verdict Friday in the trial of Derek Poulin, of Old Orchard Beach.

Investigators found no conclusive fingerprints or DNA on the murder weapons after the fire in October 2012. But prosecutors said there was plenty of circumstantial evidence pointing to the grandson of 61-year-old Patricia Noel. They say Poulin used a golf club, wrench and knife to kill her.

Defense lawyer Amy Fairfield had told jurors the real killer is free because police focused all their attention on the wrong man after a sloppy investigation.