The medical examiner has ruled the 22-year-old's death a homicide, according to Laursen, but details about how Olsen was killed have not been released.
Laursen did confirm that Olsen has a history with local law enforcement as a registered sex offender, though Laursen declined to discuss whether that criminal past may have played a part in the slaying.
BIA and sheriff's deputies found Olsen's remains about 4:15 p.m. Sunday in a wooded area near Fort Duchesne and on the edge of the Northern Ute Tribe's reservation near a home in the area of 6500 East and 1600 North.
The 7,031-square mile reservation, just east of Roosevelt and about 150 miles east of Salt Lake City, is the second-largest behind the Navajo Nation's 27,425 square miles.
According to Utah court records, Olsen was on probation at the time of his death.
In January 2011, Olsen was charged in 8th District Court with first-degree felony rape and misdemeanor unlawful consumption of alcohol by a minor.
In April 2011, he pleaded guilty to a lesser third-degree felony count of unlawful sexual activity with a minor, a statute that applies to victims who are 14 and 15 years old. Olsen was sentenced to probation and 120 days in jail.
In December, Olsen was charged with third-degree felony failure to register as a sex offender. He was sentenced in February to probation after pleading guilty to a lesser class A misdemeanor count.