Delaware's Supreme Court justices appear to have serious concerns about the validity of a search warrant that led to the arrest and conviction of a former prep school headmaster on child pornography charges.

The justices at times left a state attorney fumbling for words as he tried to defend the warrant at a hearing Wednesday in an appeal by Christopher Wheeler.

Wheeler was convicted last year on 25 counts of dealing child porn and sentenced to 50 years in prison. He waived his right to a jury trial after a judge denied a defense motion to suppress evidence seized by authorities.

Wheeler is former headmaster at Tower Hill School in Wilmington, whose graduates include former DuPont Co. CEO Ellen Kullman, U.S. Sen. Chris Coons and television personality Dr. Oz.

Wheeler's attorney, Thomas Foley, argues that authorities improperly used possible witness tampering as an excuse to obtain search warrants that contained virtually no restrictions and allowed them to search Wheeler's computers, cellphones and other digital devices for child pornography.

Foley said Wednesday that the warrant used by police was a "cut and paste job" from the type typically used in child pornography investigations. "The crime here was witness tampering," he noted.

Chief Justice Leo Strine Jr. also expressed skepticism about the search warrant, pointedly asking Deputy Attorney General Andrew Vella if it was not simply "a way to get in the door" and then rummage through Wheeler's "entire digital world." He asked Vella repeatedly, without getting an answer, why authorities would be interested in a camera if they were looking for evidence of written communications that might suggest witness tampering.