Jun 14, 2013 02:59 PM EDT By Russell Westerholm, UniversityHerald Reporter

Three Purdue University students were charged with felonies and misdemeanors for hacking professors' online grade books, the Indianapolis Star reported.

In April, the Tippecanoe County prosecutor's office charged Roy Chaoran Sun, Mitsutoshi Shirasaki and Sujay Sharma with felonies and misdemeanors including conspiracy to commit computer tampering, conspiracy to commit burglary and conspiracy to commit computer trespass.

Sun graduated with a bachelor's degree in electrical engineering in 2010, but the charges were just made public Thursday afternoon.

"This was no outside attack. This was ... students who were very smart, who decided to take their knowledge and their wisdom and used it for things they shouldn't have used it for," Purdue Police Chief John Cox said.

Cox said he and Capt. Steve Dietrich, a long-time Purdue detective, believe this kind of computer scheme to boost grades was a first for the university.

According to court documents, Sun's grade changes dated from May 2008 and continued until his final semester. The straight-A student actually had nine F's and an incomplete.

Shirasaki is charged with changing 24 grades in total between May 2010 and December 2012. He changed numerous failing grades to A's and B's and even brought to A's, which he actually earned, up to A-pluses.

Sharma was found to have changed one grade: a D into an A in an engineering class. All three majored in engineering.

In November last year, one professor of engineering reported that his password had been changed by someone else and again in December. Thus began the investigation.

The school's information technology officials determined that a hacker had changed his own grades. After contacting Purdue police in January, Shirasaki was identified as a suspect because he was logged in with his own account to the school's network at the time the hacking took place.

According to court documents, Shirasaki learned how to access professors' accounts from Sun. Their method was stealing professor's keyboards from their offices and replacing them with new ones. After obtaining the keyboard, they used a key-logging device to gain the passwords.

Sun's degree from Purdue could be revoked after a pending review currently ongoing.

Sun and Sharma are both under arrest and Tippecanoe Prosecutor Pat Harington said Shirasaki is in Japan.

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