The murder trial of 17-year-old Daniel Marsh begins today. 

Marsh is charged in the April stabbing death of an elderly Davis couple. 

"We have prepared for many months for this, as of course, has the defense," Johnathon Raven, Chief Deputy District Attorney, said.

Marsh is accused of killing Davis Attorney Oliver "Chip" Northrup and his wife Claudia Maupin in the bedroom of their Cowell Boulevard home of April 14, 2013. 

Marsh was 15 years old at the time of the murders. He is being tried as an adult on two counts of first-degree murder with special circumstances of lying in wait and torture. 

Marsh originally pleaded not guilty at his arraignment but changed his plea in June to not guilty by reason of insanity.