One of the 4 Slaughtered Idaho College Students Desperately Fought fo

One of the 4 college students found slaughtered inside an Idaho home fought with her knife-wielding attacker to the bitter end, this according to her father.

Jeffrey Kernodle was interviewed Thursday by a CBS affiliate in Arizona, revealing the body of his daughter, Xana, underwent an autopsy that proved one thing for sure ... she had "bruises" consistent with her furious battle to save her own life.

Jeffrey also described 20-year-old Xana as a "tough kid" who could succeed at "whatever she wanted to do."

As we reported ... Xana was among 4 University of Idaho students butchered inside an off-campus house with lurid images of blood leaking through the walls. 2 other roommates were inside the house but unharmed during last Sunday's attack, but they didn't call 911 for 9 hours.

The victims were identified as Xana's boyfriend, Ethan Chapin, 20, Madison Mogen, 21 and Kaylee Goncalves, 21.

Jeffrey told the news outlet he last heard from his daughter around midnight just before the attack and everything seemed fine. Jeffrey noted a number code is required to enter the residence through the front, speculating the killer was aware of that and went around back to find an open sliding door. A friend of the students who were killed has said a number of people had the code.

What's more ... cops are reportedly looking for a specific type of murder weapon -- a large combat knife similar to the one used by Sylvester Stallone's "Rambo" character in the '80s action flick, "First Blood." As for motive, police would only say the attack was targeted. The suspect is still at large.