INDIO, Calif. -

A man who beat his ex-girlfriend to death in her car and dumped her body in a Palm Springs field was sentenced today to 15 years to life in prison.

Ron Dwayne Martinez, 43, was convicted of second-degree murder on April  5 for killing 43-year-old Palm Springs resident Karyn Kleine on March 9, 2007.

Kleine's partially buried remains were found the following September, in a dirt  field, by a man walking his dog.

Prosecutors said Martinez beat Kleine, then covered her mouth, face and head with duct tape and buried her under a bush, using broken branches to cover the body.

Kleine was reported missing on March 11, 2007, by then-boyfriend Patrick Ross when she failed to show up for a lunch date and did not answer her phone.

Kleine's car was found in the parking lot at the Indio Fashion Mall on  Highway 111 and Monroe Street six days after she went missing. Blood droplets and DNA found inside the vehicle led detectives to Martinez, according to police.

Kleine's skeletal remains were found on Sept. 21, 2007, in a field at North Farrell and Tachevah drives, about a mile from her apartent. Duct tape was around the skull, according to prosecutors.

Martinez was arrested in November 2008 in Battle Mountain, Nev., a small community northeast of Reno.

He testified that he struck Kleine during an argument in her car but did  not mean to kill her.