A man already serving time in the South Dakota State Penitentiary for a rape conviction pleaded guilty Wednesday to a second rape-related charge.

Derek Pershall, 20, pleaded guilty in front of 7th Circuit Judge Merton Tice to one count of attempted third-degree rape. He could face up to 12-1/2 years in prison. A sentencing date is pending.

Pershall originally had been charged with second-degree rape.

The incident involving a female victim occurred in March 2007.

Pershall is in prison serving 12-year concurrent sentences after being convicted in Fall River County. He pleaded guilty to one count of rape and one count of sexual contact with a minor younger than 16 in 2007.