A Phoenix man accused of fatally shooting the operator of a photo speed-enforcement van has pleaded guilty to second-degree murder.

Maricopa County Superior Court spokeswoman Karen Arra says 69-year-old Thomas Patrick Destories entered the plea Tuesday, stipulating 22 years in prison. Sentencing is Aug. 20.

Destories was charged with first-degree murder in the April 19, 2009, shooting of Doug Georgianni, who was operating a speed-enforcement van on a Phoenix freeway.

Destories' trial was slated to begin in January, but his attorney requested a psychiatric evaluation, saying Destories has a history of mental illness going back to 1970.

Two psychologists examined Destories and found him competent to stand trial.