Blue Sunshine (1977). A cult classic independent film based on a bizarre series of murders in Los Angeles, as a wanted man is wrongly blamed for the murders due to circumstantial evidence. This man is on a mission to find the reason behind these murders and during his investigation finds out every killer involved in the murders had graduated from the same university 10 years ago, and every murderer at some point had taken a bad batch of LSD; nicked named "blue sunshine" back in 1967; that later causes extensive chromosomal aberrations and homicidal psychosis. He is on a mission to prove his innocence and expose what really happened.

https://youtube.com/watch?v=Xy4rVjsL8zY