Updated

Authorities have found a car believed to be related to the 1971 disappearance of two 17-year-old South Dakota girls, officials said Monday.

Attorney General Marty Jackley and Union County Sheriff Dan Limoges said the car recovered from an embankment in Brule Creek is believed to be related to the disappearance of Cheryl Miller and Pamella Jackson. The girls were last seen on May 29, 1971, driving a 1960 Studebaker Lark on their way to a party.

Jackley said Monday that the vehicle will be processed for forensic evidence.

A man already serving a prison sentence on unrelated charges was indicted for murder in the deaths of Miller and Jackson in 2007, but the charges were dropped after prosecutors found out that a supposed confession given to a fellow inmate was faked.

The disappearance of the Vermillion High School juniors was one of the initial investigations of South Dakota's cold case unit, which was formed in June 2004 to focus on unsolved suspicious deaths and disappearances because there's no time limit on filing criminal charges in homicide cases.

A September 2004 search of a Union County farm turned up bones, clothing, a purse, photographs, newspaper articles and other items, but not the car.

In a warrant authorizing the search, authorities said that David Lykken, who lived at the farm in 1971, might have been involved in the disappearance of Miller and Jackson as well as three other unnamed people. Lykken is prison serving an unrelated 227-year sentence for rape and kidnapping.

In July 2007, a Union County grand jury indicted Lykken on two counts of premeditated murder, two counts of felony murder and two counts of murder in the disappearance of Miller and Jackson. He was arrested at the prison and scheduled for a March 2008 trial, but state prosecutors dropped all six murder charges after discovering that a prison snitch made up a supposed admission.

Aloysius Black Crow pleaded guilty in March 2008 to two counts of perjury for lying to a Union County grand jury and at a court hearing. He had conspired with another inmate to tape a fake confession implicating Lykken.