The markings show this particular pistol was used both by the East German government and was later reissued by the combined Federal Republic of Germany. I purchased this pistol in the late 90’s. It was equipped with a set of thumb rest “target grips” to meet import requirements. I replaced those with the rubber Pearce Grips seen in the photo and also acquired a set of actual hard plastic East German grips later (which I couldn’t find for the photo.) In use I’ve found this pistol to be both reliable and accurate. The double-action trigger pull, while heavy, has smoothed out noticeably with use.
East German border guards had a standard procedure to follow if they detected unauthorised individuals in the border zone. (Though the West Germans referred to the control strip as a "death strip", deadly force could be used at any location along the border – it did not depend on an individual's being in, or crossing, the control strip.) If the individual was less than 100 metres (330 ft) away, the border guard would first order: "Stop! Border sentry! Hands up!" ( "Halt! Grenzposten! Hände hoch!" ) or "Stop, stand still, or I will shoot!" ( "Halt! Stehenbleiben, oder ich schieße!" ). If the individual was further away or on the Western side of the border fence the guard was authorised to shoot without warning. If the escapee was a fellow border guard, he could be shot immediately from any distance without prior warning. Border guards were instructed not to shoot if innocent bystanders might be hit or if the escapee had made it into West German territory, or if the line of fire was into West Germany. In practice, though, shots fired from East Germany often landed in West German territory. 
The question we want to answer about this sterilization is why? The break up of Yugoslavia and ensuing conflict, very similar to today’s conflict in Syria saw an enormous diversity in the trade and manufacture of small arms, going in and going out of the conflict zones as all the various armed groups tried to get ahold of weapons to arm themselves with. Sterilization almost entirely is done to allow plausible deniability to the presence of a country’s small arms in another location. China in particular made entire batches of small arms with dedicated markings such as M21 on SKS’s, complete with actual serial numbers. These were fed into Cambodia, Vietnam, and Laos during the Vietnam War. This is a photograph I took of while in Burma of one such example-