44-year-old Robert W. Ferretti has been sentenced to serve 15 years in prison in connection with the murder of Tiffany Britt Jarmon, whose body was found dumped in Logan Canyon.On the day Ferretti was to be sentenced in 1st District Court, he asked to withdraw his guilty plea but prosecutors said Utah law prohibits a person from reversing without showing a good faith reason for doing so. On Jan. 11, Ferretti had entered a plea of guilty to first degree murder after 1st District Judge Kevin Allen asked if he intentionally caused the death of Jarmon. Her decomposed body was found near the bank of the Logan River in November 2008 by a fisherman who was walking near the bottom of a steep embankment just yards from U.S. Highway 89.On Wednesday, Ferretti claimed he misunderstood what was being asked at the earlier hearing where he admitted the murder. Cache County Attorney James Swink, however, called Ferretti a dangerous person and said the facts show the defendant had a very good recollection of what happened.