Updated

Jurors have told a judge that they haven't been able to agree on a verdict in the case of a man charged with first-degree murder in the 1974 slaying of a 17-year-old girl at an Iowa farmhouse.

Judge Richard Meadows told the jury Tuesday to continue deliberating in the case against 67-year-old Robert "Gene" Pilcher. Jurors began deliberating last Thursday.

Prosecutors accuse Pilcher of fatally shooting Mary Jayne Jones at his cousin's farmhouse while his cousin was away. Authorities arrested Pilcher in 2012 after tests linked his DNA to semen stains on a blanket that was under Jones' body.

Pilcher says he's innocent. He says the semen came from a previous sexual encounter, and prosecutors offered little other direct evidence linking him to the death.