Colorado teen and girlfriend kill his grandparents for $20k inheritance

Sterling Police DepartmentBrendan Johnson

Court documents released Wednesday detail a grandson's plot to kill his grandparents—with assistance from his girlfriend—in order to reap their inheritance.

19-year-old Brendan Johnson and 18-year-old Cassandra Rieb killed Johnson's maternal grandparents, Charles and Shirley Severance, on May 20 at their home in Sterling, Colorado. The teens were arrested on June 3.

The couple told police that they began planning the murders in early May, and decided to smother the grandparents with pillows while they slept. Upon entering the home, however, they discovered that Charles was awake, and Johnson struggled with his 70-year-old grandfather. The teen told police that he tried to choke his grandfather, who may have died from a heart attack. Shirley, who was also 70, was choked by both her grandson and his girlfriend.

Johnson said that Shirley asked "Why are you doing this to me?" and offered to open her safe for him. While she attempted to enter the combination, Johnson stabbed her. Rieb also admitted her involvement to police officers.

Sterling Police DepartmentCassandra Rieb

"Together we went and we did it together," she said. "We had agreed to do it together, obviously... Like one get one and one get the other."

They told investigators that they planned to cut up and burn the bodies, but Charles was too heavy for them to move. The teens burned Shirley in a fire pit, and disposed of some of her remains in Lorenzo, Nebraska.

On May 29, Johnson called the police and reported finding his grandfather dead and grandmother missing. Shirley's remains were discovered on June 2.

Rieb said the motive for the killings was the $20,000 and modest home Johnson stood to inherit upon his grandparents' death. The Associated Press reported that the home is worth about $47,000.

Possible charges include first-degree murder, forgery, aggravated robbery, and theft. The teens are being held without bond.