I agree with Kocjo. "A German scope" doesn't mean anything regarding the truth behind the story.
The number one sniper ace of the German army was Matthäus Hetzenauer
Born 23.12.1924 in Brixen im Thale (Tirol)
Ritterkreuz on 17.04.1945 as Scharfschütze in 7./GebJägRgt 144
345 confirmed kills.
No SS officer König or Thorwald, combined with the correct rank is listed who could be him (wrong units, promoted to late, etc.) In addition: there isn't any SS officer (all ranks) listed named Thorwald on John Moore's excellent "Führerliste der Waffen-SS". Off course there were several Waffen-SS officers named König, but they all held this rank in late 1943 or even later.
No SS major (Sturmbannführer) König or Thorwald is listed in the Volksbund database. The database is incomplete, I know, but quite good when it comes to higher ranks such as Sturmbannführer. The Volksbund lists Germans who were KIA or MIA during WW1 or WW2. Nobody at all (Wehrmacht or Waffen-SS) named Thorwald is listed there. König is listed, but not with the correct time of death.
No SS member named König or Thorwald received the Ritterkreuz or the DKiG. If he wasn't fictional, he would have won at least one of them given his alleged 400+ kill score. The fact that König aka Thorwald didn't receive the RK or the DKiG certainly does not make it plausible that he existed. It's quite ridiculous to even consider the possibility of a high ranking Waffen-SS officer with an incredible number of kills who was never awarded.
Here is what Anthony Beevor (author of Stalingrad) had to say:
"Indeed, the whole story of the sniper duel is fiction. There is absolutely no trace in the German military archives or SS records of SS officer Heinz Thorwald.
Also there is absolutely no report of the duel in the Red Army files which concentrated on sniper activities (the daily reports of the Political Department of Stalingrad Front to Moscow)
This great story can be classified as Sovjet propaganda."
The quote below is from a BBC News article:
"Mr Beevor, whose acclaimed tome Stalingrad is rapidly becoming the definitive text on the battle, said while Zaitsev was a real figure there was no evidence to support the existence of Koenig.
He said: 'I've been through the Soviet Ministry of Defence's archive in Podolsk and there is no record of such a duel.'
'If it had taken place the Soviet propaganda machine would have leapt on it.'"
Addendum by Martin Pegler
Curator of Weapons, The Royal Armouries, Leeds, UK
While researching for a book on sniping, I used some contacts at Russian museums to look into the veracity of the much reported fight between Zeitsev and Koenig [Thorvald]. Despite the fact that Russian company and regimental records were faithfully kept even throughout the worst days of the Stalingrad seige, nowhere is this duel reported in war diaries. This would seem to be an odd omission, particularly in the face of the cult of 'Sniperism' that the Soviet press were so keen to extoll.
I tend to agree with Anthony Beevor's opinion that the shooting match never actually happened and was the result of propoganda reporting by the press who were always keen to promote new 'Heroes of the Soviet Union'. Apparently Zeitsev himself never confirmed or denied the event, an odd attitude in view of its apparent historical importance."