LINCOLN, Neb. (AP) — Prosecutors have dropped an assault on an officer charge against a man already serving prison time for two rapes and robberies in Lincoln.

Local media reports that a third-degree charge of assault on an officer was dismissed Wednesday against Armon Dixon. The decision came a month after Dixon was sentenced to 80 to 140 years for raping woman during a home invasion in 2009.

Dixon is also serving a 70- to 120-year sentence for raping a convenience store clerk in 2009 during a robbery.

Authorities say Dixon lunged for the gun of a police investigator who had been questioning him in 2009 about the rapes and robberies. Prosecutors say the assault charge was dismissed because prosecuting Dixon again wouldn’t be worth the cost.