Parents of Purdue student allegedly killed by roommate struggling to understand how this happened

CHICAGO (WLS) -- The parents of a Purdue University student who was found stabbed to death allegedly by his roommate are struggling to understand how this happened.

ABC News spoke exclusively with the parents of Varun Manish Chheda, 20. His roommate, 22-year-old Ji Min Sha, is charged with murder in an attack that police describe as "unprovoked."

READ MORE: Purdue murder suspect says 'I'm very sorry,' claims he was blackmailed before court appearance

Prosecutors allege that Sha stabbed Chheda, a data science major, several times in the head and neck with a folding knife that officers found on the floor near the chair where Chheda's body was discovered, according to the Journal & Courier in Lafayette, Indiana.

When he made his first court appearance, Sha said "I'm very sorry." He also claimed he was blackmailed, but didn't elaborate further.

Eva Pilgram's exclusive interview will be shown on Good Morning America Friday, right after ABC7 Eyewitness News This Morning.