Isaiah Shaffer
Isaiah Shaffer ( | )

Isaiah Shaffer, 30, was sentenced to 40 years in prison today for his part in the murder of a Denver medical marijuana provider last year.

Shaffer pleaded guilty to second-degree murder and aggravated robbery earlier. A co-defendant, Peter Bellar, 26, was found guilty of first-degree murder by a jury earlier this year and was sentenced to life in prison without the possibility of parole.

The pair were accused of robbing and killing Douglass Singleton, 58, in Singleton's home in the 2600 block of Leyden Street on January 2010.

Bellar also was wounded in the assault.

Shaffer received the maximum sentences, 20 years for second-degree murder and 20 years for aggravated robbery, according to the Denver District Attorney's Office.

"The judge ordered the sentences to be served consecutively for a total sentence of 40 years in the Colorado Department of Corrections," prosecutors said in a media release.