Murder of Kirsten Costas

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Kirsten Costas
Kirsten Marina Costas

(1968-07-23)July 23, 1968
DiedJune 23, 1984(1984-06-23) (aged 15)
Cause of deathStabbing
EducationMiramonte High School
  • Arthur Costas (father)
  • Berit Costas (mother)

Kirsten Marina Costas (July 23, 1968 – June 23, 1984) was an American high school student who was murdered by her classmate Bernadette Protti in June 1984.[1][2]


The daughter of affluent parents Arthur and Berit Costas, Kirsten Costas and her brother Peter grew up in the small suburban town of Orinda, California.[3] Costas attended Miramonte High School and was a member of the school's varsity swim team and the cheerleading squad.[4]


On June 23, 1984, Costas was lured with a phony invitation to a dinner for the Bob-o-Links, a sorority-like group at school.[1] According to Protti's later testimony, she had planned to take Costas to the party to befriend her, but Costas became angry when she was told that there was no dinner for the new "Bobbies." The girls quarreled and Costas fled to the home of Alex and Mary Jane Arnold, telling them that her friend had gone "weird."[3] When Costas could not reach her parents by telephone, Alex Arnold drove her home, noticing that the Protti family's Pinto was following them.[3] At the Costas home, Arnold, sitting in his car, saw Protti attack Costas.[5] He thought that he was witnessing a fistfight, but in fact Protti had stabbed Costas five times with a butcher knife and fled.[3] The Costases' neighbors called an ambulance, but Kirsten was mortally wounded and died at a nearby hospital.[6]

It took the police almost six months to find Costas' killer.[3] Protti passed a lie-detector test, but her alibi went unverified. After attempting to confirm Protti's alibi, police suspected that she had lied. Following a conversation with an FBI agent who informed her that her arrest was imminent and that they knew that she had killed Kirsten, Protti wrote her mother a letter in which she made a full confession.[7]

Protti claimed to have found the kitchen knife by chance, and her elder sister, Virginia Varela, testified in court that she kept that knife in her car to cut vegetables.[3] The Costases did not believe Protti's story; they asserted that nobody would use an 12-inch-long butcher knife to slice tomatoes and that Protti, casually dressed that evening, never intended to take Kirsten to a party but had planned to murder her.[citation needed]


The Costas family left Orinda and moved to Hawaii in 1986.[8]

Protti was sentenced to a maximum of nine years, but was released seven years later in 1992 on parole at the age of 23. Costas' parents vehemently opposed Protti's release.


American filmmaker James Benning covered the aftermath of the murder in his 1987 documentary Landscape Suicide.[9]

In 1994, the story was made into a television movie entitled A Friend to Die For (also known as Death of a Cheerleader), with Tori Spelling as Stacy Lockwood, a character based on Kirsten Costas and Kellie Martin as Angela Delvecchio, a character based on Bernadette Protti.[10]

The aforementioned film was remade in 2019 as a Lifetime television movie starring Aubrey Peeples as Bridget Moretti and Sarah Dugdale as Kelli Locke, characters based on Protti and Costas, and Kellie Martin, who played Protti in the first television movie, playing the FBI Agent charged to tracking her.[citation needed]

Costas' murder was featured in season 5 of Deadly Women, season 1, episode 3, of Investigation Discovery's The 1980's: The Deadliest Decade, and an episode of Killer Kids titled Rumors & The To-Do List.[citation needed]


  1. ^ a b "Girl, 16, Convicted in Classmate's Slaying : Teen-ager Feared Victim 'Was Going to Tell People I Was Weird'". Los Angeles Times. March 14, 1985. Archived from the original on May 10, 2012. Retrieved September 28, 2011.
  2. ^ "The State". Los Angeles Times. April 2, 1985. Archived from the original on December 22, 2014. Retrieved September 28, 2011.
  3. ^ a b c d e f Lubow, Arthur (May 12, 1985). "In a Deadly Explosion of Teenage Unhappiness, One Life Is Cut Short, Another Blighted by Murder". People. 23 (19). Archived from the original on August 20, 2019. Retrieved August 20, 2019.
  4. ^ "Calif. murder suspect, 16, called polite, loving person". Courier-Post. Associated Press. December 15, 1984. p. 3A. Archived from the original on August 19, 2019. Retrieved August 19, 2019 – via icon of an open green padlock
  5. ^ O'Connor, John D.; Matier, Phil (March 12, 1985). "FBI witness ties jealousy to Costas murder". The San Francisco Examiner. p. B1. Archived from the original on August 19, 2019. Retrieved August 19, 2019 – via icon of an open green padlock
  6. ^ Douglas, John E.; Burgess, Ann W.; Burgess, Allen G.; Ressler, Robert K. (2011). Crime Classification Manual: A Standard System for Investigating and Classifying Violent Crimes (2 ed.). John Wiley & Sons. pp. 173–175. ISBN 978-1-118-04718-7. Archived from the original on 2021-07-18. Retrieved 2019-08-20.
  7. ^ "'Bernadette Protti, Kirsten Costas: Cheerleader Murder On ID's '1980s The Deadliest Decade,' Plus The Obsession With Finding Bernadette Protti". The Inquisitr. April 3, 2017. Retrieved July 18, 2021.
  8. ^ "Protest over parole of schoolgirl's killer". The San Francisco Examiner. Associated Press. June 26, 1992. p. A6. Archived from the original on August 19, 2019. Retrieved August 19, 2019 – via icon of an open green padlock
  9. ^ Kehr, Dave (February 5, 1987). "Chilling film examines 'Landscape' of murder". Chicago Tribune. Archived from the original on July 18, 2021. Retrieved August 20, 2019.
  10. ^ Kovalchik, Kara. "Five murders and the movies they inspired". CNN. Archived from the original on December 27, 2017. Retrieved December 26, 2017.