three-quarters of mile away and found the Piper PA-32 plane.

"The debris field is quite extensive," Fulkerson said. "The plane suffered a lot of damage on impact. We have two independent eye witnesses that said that the aircraft appeared to be coming apart while in the air."

Fulkerson said Hansen sent a text to the family about severe weather while flying over Rolla at 7:40 a.m.

As of right now, officers do not know the exact cause of the crash.

"Only thing we can speculate here is that he was trying to land due to some problems," Fulkerson said. "That he was having problems would be the only explanation why he was heading back to this airport.

The Federal Aviation Administration has not immediately returned a phone call or message for comment.The textbooks are among the first 16 reviewed by state education officials as part of the Digital Textbook Initiative launched by Schwarzenegger in May.

The report released Tuesday is intended to help local school districts identify online learning materials that meet state math and science standards.

State officials plan to review digital textbooks for other academic subjects in coming months.

The governor is promoting digital textbooks to help districts save money and create more interactive learning environments, but experts say many California schools don't have enough computers to take advantage of them.