ORLANDO, Fla. — The last of four people convicted of stealing moon rocks from a NASA safe and trying to sell them was sentenced Wednesday to more than eight years in federal prison.

Thad Roberts, 26, a former intern at the Johnson Space Center in Houston, pleaded guilty in December to stealing the rocks, which have been valued at between $2.5 and $7 million. The rocks came from every Apollo mission from 1969 to 1972.

As part of his plea, he also admitted stealing dinosaur bones and fossils from a museum at his school, the University of Utah. Those items were found at his home soon after his arrest.

Roberts was arrested in an FBI sting that began when a Belgian rock collector alerted investigators to Internet offers to sell moon rocks for $1,000 to $5,000 a gram.

The rocks were recovered in July 2002 at an Orlando hotel after undercover FBI agents used e-mails to negotiate their purchase.

Roberts' co-conspirators and fellow interns Gordon Sean McWhorter, Tiffany Fowler and Shae Sauer were all convicted. McWhorter was sentenced to more than five years in jail, while Fowler and Sauer were sentenced to 180 days house arrest and ordered to pay more than $9,000 restitution to the space agency.