How about any of these? Some have been suggested as serial killer victims, but that's not definite proof they are (remember Leonard Fraser).
https://www.findthemissing.org/en/cases/31371/270 - Patricia Taylor, 14, January 1st 1980, OK. Would have been 15.
https://www.findthemissing.org/en/cases/12215/280 - Julie Hill, 22, July 18th 1980, MN. Would have been 22.
https://www.findthemissing.org/en/cases/4571/249 - Lucinda Schaefer, 16, June 24th 1979, CA. Would have been 17.
https://www.findthemissing.org/en/cases/4594/135 - Barbara Glueckert, 14, August 11th 1974, IL. Would have been 20.
https://www.findthemissing.org/en/cases/2555/98 - Janice Pockett, 7, July 26th 1973, CT. Would have been 14.
https://www.findthemissing.org/en/cases/1721/242 - Katherine Anderson, 24, April 20th 1979, MD. Would have been 25. Looks younger than 24.
https://www.findthemissing.org/en/cases/12102/253 - Norma Halford, 21, August 24th 1979, CO. Would have been 22.
I can't believe it's been 35 years. I know I suggest Janice Pockett for everything (especially the Lime Lady), but I don't want to rule out anything. Remember, if you eliminate the impossible, whatever remains, however improbable, is the answer.