Masked intruders broke into the Moscow region branch of the Investigative Committee early Tuesday, rifling through 18 offices and cracking open 25 safes after tying up the sole security guard, investigators said.
But the Investigative Committee's main office insisted that the mysterious break-in was a run-of-the-mill robbery, fueling speculation that the incident was an attempt to undermine a high-profile criminal investigation.
Three masked intruders broke into a building belonging to the committee's Moscow region branch on Rusakovskaya Ulitsa in northeast Moscow at about 4 a.m. Tuesday, the Investigative Committee said in a statement.
It said the assailants only took a television set and a video camera.
"No criminal files and no evidence were taken," the statement said.
It said the intruders were probably looking for valuables and linked the incident to a similar break-in at a neighboring pharmaceuticals company the same night.
National media were rife with speculation that the intruders had other motives.
The contents from all 25 safes were strewn over the floor except for one safe, whose documents were missing, Lifenews.ru reported, quoting a source in the committee's Moscow region branch.
The same news site reported later that an unspecified amount of jewelry and stacks of stationery with official letterhead were missing. The jewelry had been kept in an envelope belonging to an ongoing criminal investigation, it said.
The blank letterheads were used for official communication with police, the report said, quoting an unidentified local Investigative Committee official.
The office's sole guard was unarmed, national media reported.
A branch spokeswoman denied reports that the robbers might have made off with documents about a corruption case against Yury Sleptsov, mayor of Voskresensk, a town southeast of the capital.
Interfax quoted an investigator working at the scene as saying material from "one high-profile case" was missing.
"I do not exclude that the culprits were looking for a certain criminal case," the investigator said, adding that it might be a case against Sleptsov.
The mayor was detained in July on accusations of extorting a bribe of more than $17,700 for a permit. On Monday, the Moscow regional branch of the Investigative Committee said it had opened another investigation into Sleptsov, for possible abuse of office.
Sleptsov faces up to 12 years in prison if convicted on the graft charges.
Branch spokeswoman Yulia Zhukova said no files on the case were held in the burgled office. Rather, Sleptsov's files are stored in the branch's headquarters on Maly Kiselny Pereulok, she said by telephone.
The burgled office houses the committee's "important cases" department, which deals with serious crimes like murder, rape and organized crime, Zhukova said.
The Moscow region has seen a string of unsolved attacks on journalists, including Mikhail Beketov, editor of Khimkinskaya Pravda, who regularly wrote about corruption among local officials. Beketov was left brain-damaged after being severely beaten outside his home in 2008.
National media reported Tuesday that the robbed office had dealt with Beketov's case. It also worked on the case against Lieutenant-General Vladimir Shamanov, who has been accused of dispatching his commandos to block a criminal investigation into his son-in-law, the reports said.
Moscow region Governor Boris Gromov, who commanded the 40th Army during the Soviet war in Afghanistan, has helped many fellow Afghan war veterans obtain posts in the local government, including Sleptsov and Khimki Mayor Vladimir Strelchenko.