SAN DIEGO -- Several students are suspected of hacking into the San Dieguito Union School district's computer system and could face criminal prosecution, 10News reported.

It's believed that the students changed some grades and snatched some tests.

But both the school district and the sheriff's department are investigating and the penalty could be harsh.

The sheriff's computer and technology crime high tech response team (CATCH) office focuses primarily on computer crimes, tracking down bad guys with state of the art software.

Hackers recently broke into the San Dieguito Union High School district computer system, so the CATCH team started by examining the main computer and working backwards.

"We use specific programs to forensically copy (and a) mirror image of (the) hard drive. (We) run the programs to look at the data on that hard drive (and) follow back the clues left behind -- that's how we track cases," said CATCH team commander Terry Jensen.

Those clues can be substantial and could lead directly to suspects and arrests -- it just takes time and effort.

"Each computer contains information on (a) hard drive, (so we) track the computer and computer usage," said Jensen.

It's not a slam dunk, though. Technology improves constantly.

"One of the difficulties with computer crimes is (the) sophistication of those hacking into systems. Once they learn you're looking, (they) make themselves that much more difficult to identify and hold accountable," said Jensen.

The hacking into the San Dieguito school system may be limited to stealing tests and changing grades, but investigators are looking at how far-reaching the crime is and how serious.

"We don't see anything that leads us to believe identity theft or credit theft -- that's much more urgent, but we're working on overtime, working on this full time," said Capt. Glenn Revell, with the sheriff's department.

Teachers have been advised to compare the grades in their files with those now in the computer and some tests may have to be revised.

Depending where the investigation leads, the crimes carry up to a three-year prison term and a $10,000 fine.