I think, it's a variant of SECHRIST:
http://www.ancestry.com/search/SurnamePage.aspx?sourcecode=13304&html=b&fn=&ln=sechrist&submit.x=0&submit.y=0
The German word "Sigrist" is not in use any more (except in Switzerland). The name SECHRIST is *very* rara in Germany, as SECHRIEST it is almost nonexistant (5 or 6 hits at Google on German sites). I have never heard of either.