I came across the entry for Walter Spitthoff in the Vermisstenbildliste (XB, 423) and decided to do a quick name search, which ended up turning into a few hours of research. In the end there is not very much out there.

According to Luftwaffedata he was piloting an Me-210 that went missing on Feb. 22, 1943. (They refer to this in a note rather than include it in the daily log.)
http://luftwaffedata.co.uk/wiki/inde...#_ref-ftn202_0

According to Robert Forsyth in Me 210/410 Zerstörer Units "exactly two weeks" after an Me-210 from 2(F)/122 went missing on Feb 8, 1943, and Me-210 piloted by one "Walter Spitzmer" went missing, possibly shot down by Spitfires from No. 145 Squadron. (This book is the only reference to this name that I can find, so I'm assuming this is referring to Walter Spitthoff going missing on Feb 22.)

photo
https://imgur.com/a/fS4AGcS