(Peter Cade/Iconica/Getty Images)

ABC News’ Jenna Harrison reports:

Students at a private northern California university got a surprise after a hacker entered the university’s computer records database and changed their grades for the better.

More than 60 current and former undergraduate students at Santa Clara University had their grades altered after someone hacked into school records, according to Santa Clara University Provost Dennis Jacobs.

In August 2011, a former undergraduate student notified school officials after noticing the grades on her transcript were different than she remembered.

Santa Clara officials began investigating current and former undergraduate students’ records.

“We internally examined over 50,000 records in the system dating back to 2000,” Jacobs said.

After a few days of their own investigation, officials contacted local authorities, who turned the investigation over to the FBI.

Investigators were been able to determine that the hacking occurred between June 2010 and July 2011, but no arrests have been made.

The hacker made grade improvements that ranged from changes from  F to A, while others  students’ had slight changes, such as from B to B+.  The first incident of grade modification occurred in 2004 and continued through spring of 2011.

According to Jacobs, professors with legitimate reasons may submit change of grade forms with the registrar’s office. Authorities were able to trace the grades hacked due to the lack of proper documentation.

“(The university) has tightened all security protocol including enhancing grade security and working with a third party consulate to improve security measures,” Jacobs says.

The university has since implemented a system to check the grades of the more 5,000 undergraduate students each night.

“We use manual verification to make sure all the changes are legitimate,” Jacobs said.

School officials say there is no evidence that student, faculty or staff personal information was involved in the hacking.

“The target of intrusion appears to be only related to grade changes,” Jacobs said.

Investigators said there is no specific connection between the students affected.  Students from all majors were targeted, including those in the College of Arts and Sciences, the School of Engineering, and the Leavey School of Business.

The university is looking at all the facts and circumstances around the hacking, and Jacobs said the university will take action if any current or former students are found to be involved.

“The university takes this intrusion very seriously,” Jacobs said. “Our students and their grades are very important to this institution and we are working to restore the integrity of our grade records.”