The 8 Jul 1964 DV announced that producer-director William Castle was currently preparing Out of the Dark, based on the soon-to-be-released novel, Out of the Dark, by Ursula (Reilly) Curtiss. The 5 Aug 1964 Var explained that Castle had purchased rights to the novel prior to its anticipated Sep 1964 publication.
       The 9 Jul 1964 DV reported a title change to In Case of Emergency, and stated that the feature would be co-produced by Universal Pictures. William McGivern was adapting the screenplay, and Merrie Spaeth and Tippy Walker were in talks to play the teenaged leads. The 5 Aug 1964 Var noted another title change to In Case of Murder, and announced that filming was expected to begin in mid-Oct 1964 at Universal Studios in Universal City, CA.
       According to the 16 Sep 1964 Var, Castle was unable to secure Spaeth and Walker for the principal roles, and casting difficulties had caused production delays on the picture, now titled I Saw What You Did. Castle was said to be considering Pamela Franklin for one of the teen characters, and was searching for an adult actress “like Greer Garson” for the adult lead. On 23 Sep 1964, DV announced that Joan Crawford had been cast in a lead role.
       An18 Sep 1964 DV production chart and the 25 Sep 1964 DV listed a 26 Oct 1964 start date. However, the 23 Oct 1964 DV production chart and the 30 Oct 1964 DV reported that filming would begin on 2 Nov 1964, and added John Ireland and Tom Hatten to the cast.
       The 4 Nov 1964 Var announced the casting of teen leads Andi Garrett and Sarah Lane. The novice actresses, making their feature film acting debuts, had been discovered through a Los Angeles, CA, radio station contest, and won out over 400 other contestants.
       Joan Crawford’s role amounted to a “three-day cameo,” during which “she slept in her studio dressing room,” according to the 4 Nov 1964 LAT. William Castle praised Crawford’s coaching of the inexperienced young leads in an 18 Nov 1964 DV item, stating that she devoted several hours tutoring the girls in acting techniques. Castle purposely chose non-actors who would appear natural onscreen. He planned to enlist Crawford in future endeavors dealing with new talent, giving her an assistant to the producer-director credit. Two additional newcomers reportedly signed to the cast were Janet Hamill and John Crowther.
       Production was still underway at Universal Studios as of 16 Dec 1964, as noted in that day’s Var.
       The world premiere was held simultaneously at the State Theatre in Minneapolis, MN, and at the Paramount Theatre in St. Paul, MN, on 14 May 1965, according to the 19 May 1965 DV. The 2 Jun 1965 Var stated that Castle, who spent a week in Minnesota promoting the picture, specifically chose those cities to prove that a properly promoted picture “could do good business” anywhere. After three days in release, box-office receipts totaled $16,707 from both theaters.
       The picture opened in New York City theaters on 21 Jul 1965, on a double-bill with Dark Intruder (1965, see entry), as announced in the 22 Jul 1965 NYT review. Joan Crawford, Andi Garrett, and Sarah Lane made personal appearances at fifteen of the twenty six theaters where the film screened, as stated in the 21 Jul 1965 Var. The 29 Aug 1965 LAT noted that the Los Angeles-area opening would be held on 1 Sep 1965. In a 12 May 1965 review, Var described I Saw What You Did as “well-made” with a “better-than-usual story line” for the suspense-terror genre. Crawford’s performance was praised, as were the scene-stealing debuts of teenagers Garrett and Lane.