Inv. Michael Aluffi:   Did you ever have any kind of a sexual achievement while you were killing them [his victims]?

Kemper:  Yes, I’m sure it’s happened before, but the only time I actually noticed an ejaculation was as I was killing Mrs. Hallett on Saturday night, as she was dying, it was a great physical effort on my part, very restraining, very difficult, much less difficult that I made it, I went into a full complete physical spasm let’s say. I just completely put myself out on it and as she died, I felt myself reaching orgasm. In the other cases, the physical effort was less. I think with the Koo girl, in the case of a suffocation, the same thing happened. But I didn’t really notice it, because I did have sex with her right after causing her to be unconscious. 

Source: Excerpt from Ed Kemper’s official jailhouse confessions in Santa Cruz on April 28, 1973 (after his arrest in Pueblo, Colorado), pages 27 and 28 / Video of confessions from the Oxygen documentary Kemper on Kemper (2018)