3 Young Girls missing in 1981 One found murdered 2 never found where they connected?

I In an earlier article I covered the case of a Young Girl Christine Gunther who went missing in November of 1981 and was found couple days later murdered and in months leading up to her disappearance and murder 2 more young girls disappeared  never to be found 

http://www.post-gazette.com/local/south/2011/11/06/Murder-case-cold-for-30-years-warms-up-after-

Michelle Reidenbauch went missing in September of 81 in Zelinople and  and  Toni Lynn Mcnatt in November of 81 in Clairton 

http://news.google.com/newspapers?nid=1144&dat=19820627&id=mMMdAAAAIBAJ&sjid=qWEEAAAAIBAJ&pg=5341,4798500

http://news.google.com/newspapers?nid=1144&dat=19811219&id=e4sqAAAAIBAJ&sjid=fF0EAAAAIBAJ&pg=3571,1959989

http://news.google.com/newspapers?nid=1129&dat=19811125&id=JNVRAAAAIBAJ&sjid=_m0DAAAAIBAJ&pg=3170,4628358

http://news.google.com/newspapers?nid=1129&dat=20060922&id=8PFRAAAAIBAJ&sjid=V3IDAAAAIBAJ&pg=6283,702134

All 3 disappearing under similar circumstances . The work of a Serial Killer? very possible  and there has been no answers in all 3 cases.