Katyn comes up frequently, so I'm putting these two books of Russian reports here.
Germans in Katyn: Documents on the shooting of Polish prisoners of war in the autumn of 1941
Katyn. Prisoners of Undeclared War
The first book is the "if we get caught, blame it on the Germans" collection. The second book is the "hide it from the Poles, so we don't get caught" collection.
They're all in Russian, but have transcriptions. Set your browser to auto-translate Russian to English, and they're readable.
False eyewitness reports from forced Soviet perpetrators and collaborators:
Minutes of interrogation of witnesses in the case of the fascist provocation of the Katyn forests. 26.8.43. RGASPI 69-1-750. pp. 61-62.
During one visit, in a private conversation, when Karasev asked, "How are you doing?", Vinokurov replied: "Very badly, because our team of 60 people is engaged in very dirty work.
We are digging up corpses at the Smolensk cemetery, putting them in coffins, and transporting them in closed trucks to the Katyn forest, where we dump the corpses out of the coffins into large pits and bury them."
The discovery of the corpses and their transportation to the Katyn forest is
confirmed by local residents: Mikhail Semenovich Frolov, residing in Smolensk at 21 Bolshaya Sportivnaya Street, and Praskovya Kuzytina, residing in Smolensk near the New Factory. The latter claims that during the exhumation she saw remnants of cloaks belonging to Red Army officers. Vasily Andreevich Peregontsev, residing in Smolensk on Zapolnaya Street, who worked as a shoemaker at a German hospital, claims that the commission in the Katyn forest found only 900 corpses, while the Germans are reporting 12,000. Dr. Nikolai Borisovich, a resident of Rostov, living on 4th Line, went on an excursion with German doctors and participated in the commission for the exhumation of corpses in the Katyn forest. He examined the corpses and read the commission's report. According to him, the commission found 900 corpses, not 12,000, as the Germans are writing. During the examination, it was completely impossible to determine the nationality of the corpses. However,
as part of the excursion, they were shown several items of Polish origin, such as coins, cigarette cases, a mouthpiece, buttons, and rings.
Link
I remember another excursion where people were shown several items of German origin, such as lampshades and shrunken heads.
I haven't had time to go through all of the reports yet, but others might find some useful material in them.