Is ‘I Know What You Did Last Summer’ Based on a True Story?

“My daughter Kait was chased down, and her brains were blown out… So I’m particularly sensitive about desensitizing kids to violence.”

Kait Arquette was killed by the man police found next to her body… and never interviewed.

I Know What You Did Last Summer (1997) is an iconic 90s horror movie starring Jennifer Love Hewitt, Freddie Prinze Jr., Sarah Michelle Gellar and Ryan Phillipe. Anne Heche also has a smaller role, but blows it out of the water with her performance as a creepy hick. The plot follows the group of four friends the summer after they graduate from high school. After spending the fourth of July partying on a beach, they take a winding South Carolina road — the same road that was used for shots of the California coast in Hitchcock’s The Birds (1963) — and accidentally hit a pedestrian. Worried about their futures if they go to the police, the friends decide to dump the body in the ocean and never speak of the night again. However, the following summer they start getting menacing notes saying “I know what you did last summer”, and are then hunted down by a hooded figure in a fisherman’s slicker who has a hook for a hand.

This winding road was also used for scenes in The Birds (1963).

Most people might recall that I Know What You Did Last Summer is based on a 1973 young adult fiction book of the same name by author Lois Duncan. You might even recall that Duncan hated the adaptation and spoke out against violence in cinema when it was originally released. But did you know the reason for this was that Lois Duncan’s daughter, Kaitlyn Arquette, was murdered in 1989 and the case wasn’t solved until August of 2021?

In her own words, Lois Duncan grew up as a shy bookworm who sold her first short story at the age of 13. She was accepted to Duke but dropped out when she got married. After divorcing that husband in 1962 she supported herself by writing for greeting cards and pulp magazines before establishing herself and selling novels. Her first book Ransom was about a group of high school students being held hostage on a schoolbus. In 1973 she published I Know What You Did Last Summer, a fairly tame suspense novel not at all like the gory slasher movie. Wes Craven directed a TV movie of Duncan’s novel Summer of Fear in 1978. Her 1978 novel Killing Mr. Griffin, considered controversial for the portrayal of students getting revenge against a teacher, was made into a TV movie starring Jay Thomas, Scott Bairstow, and Mario Lopez in the late 90s. Around that time Duncan sold the film rights to I Know What You Did Last Summer for $150,000, and no claim to any residuals.

Lois Duncan on Unsolved Mysteries.

When the violent adaptation appeared in theaters a few years later, Duncan had harshly criticized the film as “worse than bad. It’s totally sick.”

The gore was beyond belief. I write suspense and scary stuff, but I have never written gore in my entire life. I have never sensationalized violence. It’s always been a vehicle to show the pain that violence can cause. There’s so little connected to my book (in the movie) that I don’t know why they ever wanted it.

Lois Duncan, reacting to the adaptation of I Know What You Did Last Summer in Albuquerque Journal

The reason Duncan responded so strongly to the sensationalized slasher movie version of her work is that between the writing of her horror/suspense works and the film adaptation, her daughter was murdered. She told the Chicago Sun-Times: “My daughter Kait was chased down, and her brains were blown out… So I’m particularly sensitive about desensitizing kids to violence and turning murder into a game.” Deeply traumatized by her daughter’s sudden violent death, Lois Duncan stopped writing horror and suspense novels. Her later works were children’s books and prose and poetry about losing her daughter. It turns out that the killer even read Lois Duncan’s book, Who Killed My Daughter?: The Startling True Story of a Mother’s Search for Her Daughter’s Murderer.

Duncan’s daughter, Kaitlyn Arquette, was only 18 and a recent high school graduate when she was gunned down in her car on July 16, 1989 in Albuquerque, New Mexico. An unskilled police investigation labeled the murder “a random drive by” and left the case unsolved for over 30 years. A segment about the murder even appeared on Unsolved Mysteries during the height of the iconic show’s popularity. When police arrived at the scene, they found a man named Paul Apodaca standing by Kaitlyn’s car. He was never interviewed about that night. 31 years later Apodaca confessed to murdering Kaitlyn, he said his motive was “hatred for women”. Sadly Lois Duncan died in 2016 and never saw justice for her daughter.

The production company who made the 1997 film said the fact that Duncan’s daughter had been murdered was “not well known” by the people who made the film. The source material, Duncan’s 1973 novel, was written over a decade before her daughter’s murder so there’s no way in which the film is based on Duncan’s daughter or any kind of true crime story. The ties to real life crimes in this case only highlight the anguish of a mother whose daughter’s murder investigation was egregiously botched by police, understandably giving her a distaste for violence, including later adaptations of her works.

Paul Apodaca through the years, via the Albuquerque Police Department

I think that what happened was Apodaca was a serial murderer who was out hunting for young women because he didn’t get lucky… He was angry at females and he was out just hunting, and he shot Kait because she happened to be there.

Kerry Arquette, Lois Duncan’s older daughter who became a criminologist after her sister’s murder, on Paul Apodaca.

I Know What You Did Last Summer got two sequels, the theatrical I Still Know What You Did Last Summer (1998) with Jennifer Love Hewitt, Freddie Prinze Jr., Brandy and Mekhi Phifer, and the straight-to-DVD I’ll Always Know What You Did Last Summer (2006).

Kevin Williamson wrote the script for I Know What You Did Last Summer some time in the early 90s and after the success of Scream (1996) it was bought and put into production.

Around 2014 an I Know What You Did Last Summer remake was considered and a script was written by Mike Flanagan and Jeff Howard who have since worked together on fan favorite projects like The Haunting of Hill House and Midnight Mass. The script would also not be based on Lois Duncan’s daughter or any other true story. It would have strayed further from the source material and have taken place in Antigua where a group of American friends are celebrating the end of high school. Drugs cause one of the friends to hallucinate and he comes to in a police station where he is being questioned for the disappearance of a local woman he had been partying with. The trial becomes a media circus and although eventually freed, all the friends are stalked by infamy and warnings that someone “knows what they did last summer”. Ideally Jennifer Love Hewitt would have an extended cameo as the producer of one character’s true crime podcast.

The entire thing in our minds was designed around a really cool trick ending that got us really excited. Like a real, Witness for the Prosecution-style nod of an ending where something comes in and blows things up in a way that – you could’ve seen it all along, but you never would have seen it. That kinda deal. It was just so much fun, but it was a big controversial ending from the very moment of the pitch. Literally, I think 99% of the interest from me and Mike was that ending. It was really cool to us.”

Jeff Howard, on his unmade I Know What You Did Last Summer remake

Eventually a different remake was made by Sony as Prime series, produced by James Wan, but it got terrible critical and commercial reviews. Now that there is more closure in Kaitlyn Arquette’s murder case, I would be interested in a faithful adaptation of Lois Duncan’s real life and her struggle to come to terms with the horror content she had written for entertainment value in the wake of her very real tragedy. Can we get Sarah Paulson on this?

Meet The Author

Chrissy Stockton

Chrissy is the co-founder of Creepy Catalog. She has over 10 years of experience writing about horror, a degree in philosophy and Reiki level II certification.

Chrissy Stockton