Kirsten Costas

About Kirsten Costas

Kirsten Marina Costas (July 23, 1968 – June 23, 1984) was an American high school student that was murdered by her classmate, Bernadette Protti, in 1984.

The daughter of well-to-do parents, Arthur and Berit Costas, she and her brother Peter grew up in the small suburban town Orinda, California. Costas went to Miramonte High School, and was a member of the school's varsity swim team and the cheerleader squad.

On June 21, 1984, Costas' mother received a phone call from a girl who claimed to be one of the "Bobbies" (i.e., "Bob-o-links", a sorority-like group at school) telling Berit Costas that Kirsten was invited to a dinner for the new group members. According to Protti's later testimony, she had planned to take Costas to the party to befriend her, but Costas got angry when she was told that there was no dinner for the new "Bobbies". The girls quarreled, and Costas fled to the Arnold family living nearby, telling them that her friend had gone "weird". When Costas could not reach her parents by telephone, Arnold drove her home, noticing that a Pinto – the Protti's family car – was following them. At the Costas' home, Arnold, sitting in his car, saw Protti attack Costas. He thought he was seeing a fist-fight but, in fact, Protti stabbed Costas five times with a kitchen knife and fled. The Costas' neighbors called an ambulance, but Costas was mortally wounded and died at a nearby hospital.