Yuri Yudin had left the team a few days before the incident occurred. He could not know anything valuable about DPI and how it was investigated.
I think it makes sense to clarify a little bit what was behind the investigation that was run by Tempalov and Ivanov in 1959. And here it is very important to understand that neither Tempalov nor Ivanov had ever been leading investigators (owners) of the case.
The only case related to DPI was initiated by the special prosecutor’s office responsible for overseeing the facility that conducted some technology tests, and then transferred to the Prosecutor’s Office of the USSR. The basis for initiating the case was an accident that occurred during the tests. The case was against designers or production personnel, who were to be held accountable for the accident. The deceased tourists had nothing to do with the case at the beginning. Perhaps, if it weren’t for the technology accident, no case would have been initiated at all. And when it turned out that the failed test also resulted in the deaths of 9 civilians, this episode had to be included in the charges against the individuals involved in the case. That is why the Prosecutor’s Office of the USSR tasked the Prosecutor’s Office of the Sverdlovsk Region with gathering materials on this episode.
And then everything went in full compliance with the requirements of the Criminal Procedure Code of the RSFSR, except for the fact that the case being investigated was classified as secret. Therefore, not all those who carried out investigative assignments for the USSR Prosecutor’s Office knew who they were working for or what case was being investigated. And measures were taken to conceal the purpose and direction of the investigation.
What had evidentiary value for the case was sent to Moscow. But in such complex case, a lot of unnecessary junk documents inevitably had to appear — junk that could not be allowed to clutter the case being investigated by the USSR Prosecutor’s Office. Therefore, such junk had to be cut off and left in Sverdlovsk. The only possible and reasonable way to do this was to create a separate case files for it. That’s where the useless paper waste was dumped. The Moscow investigation group, apparently, requested these case files, taking from them whatever might be useful for their real case files. After that, Moscow returned all the scraps to Sverdlovsk to be deposited in the archive of the Sverdlovsk Regional Prosecutor’s Office, Moscow had no use for that junk.
The case that the USSR Prosecutor’s Office had investigated was either terminated or sent to one of the special courts and ended with a court verdict. In the first case, it is stored in the closed archive of the USSR Prosecutor’s Office; in the second case, in the archive of one of the former special courts.