A judge has entered a not guilty plea for a 22-year-old Idaho man charged with killing a former Arizona power company executive, his wife and their adult son at a Boise home.

Adam Dees of Nampa appeared Thursday in 4th District Court but declined to enter a plea.

He's charged with three counts of first-degree murder as well as robbery and other crimes.

Prosecutors allege Dees killed 80-year-old Theodore M. Welp, 77-year-old Delores Elaine Welp, and 52-year-old Thomas P. Welp on March 8 or 9.

A grand jury indictment says all three victims were shot in the head and beaten with a baseball bat.

A trial is been set for Sept. 29. Dees is jailed without bond in Ada County.