Intentional damage to a Proton rocket booster was reportedly established by a polygraph and a criminal case has been initiated, Izvestia daily quotes the Ministry of Interior. Previously sabotage was considered an unlikely option.

An investigation into the Proton-M rocket crash in April 2013 conducted by the Federal Security Service (FSB) has resulted in establishing general proof that foreign matter could have been deliberately placed into crucial components of the booster in order to provoke malfunction - at the factory where the boosters are assembled.

As Izvestia found out, the Ministry of Interior launched a criminal case of "Intentional destruction or waste of property which caused human death through negligence or other grave consequences."

It has now been leaked that the cause for a special investigation occurred back in April 2013, when X-raying at an incoming control checkpoint detected several unused aluminum tube seals inside the air duct supply of the second stage engine RD-0210. If the fault had not been noticed, it would have resulted in yet another crash of the booster.

Emergency malfunction repairs cost about $6,000, and the $83 million launch of a booster (excluding the vehicle it was launching) was saved.

Initially the security structures of the Khrunichev State Space Research and Production Center, where Protons are produced, did not pay serious attention to the incident, writing it off as an accidental assembly fault.

But when the FSB was informed about the incident, it launched a lie detector probe of about 15 assemblers who could have been in physical contact with the duct during the assembly, a source at the Khrunichev Center told Izvestia.

The results of the FSB investigation were delivered to the Ministry of Interior and became the basis for the criminal case. The names of the established suspects have not been made public for legal reasons, a source in the ministry informed Izvestia.

Officially, the Khrunichev Center made no comments, but Izvestia's source at the center familiar with the situation said that incidents with foreign objects had taken place before.

"They don't report such things because they're not sure whether it was done intentionally or not," the source claimed.

For example delivery of 20-ton multipurpose lab module for the ISS supposed to get into space in March 2014 was postponed for 2017 as pre-start quality control service at Baikonur Cosmodrome allegedly found 'metal shavings' in the ducts of the module.

How this could be possible if the Khrunichev Center has a strict quality control service of its own remains a matter of yet another investigation.

According to Izvestia, the management of the Khrunichev Center has been officially warned against concealment of such facts in the future.

So far the extent of culpability of the Khrunichev Center's staff is yet to be established, but the source in the Ministry of Interior suggested that one of the possible reasons for willful damage could be low salaries at the center, which on the average are about $1,000 per month.

When a Proton-M rocket with Russia's most powerful Express-AM4R communication satellite crashed on May 16, the cost of the lost spacecraft summed up to $225 million, but what's even more important a significant part of Russia was left without hi-speed internet and HD television in remote areas.

Two weeks after the crash the chairman of the inter-body commission investigating the incident, Aleksandr Danilyuk, said that "sabotage has not been ruled out."

But the expressed sabotage theory caused such hype in Russian media that it drew a rebuke from Deputy Prime Minister Dmitry Rogozin, who supervises the Russian space industry.

"The Roscosmos disaster commission should first finish its work and present the results to the Russian government, and only then torment society with new theories as to what happened," he tweeted.

This was Russia's third launch of Express series satellites this year. In March, Express-AT1 and Express-AT satellites were successfully put into orbit.

A predecessor communication platform, Express-AM4 satellite was also lost in a similar Proton-M booster crash in August 2011.

Talks about intentional damage caused to Proton boosters particularly intensified last year after a catastrophe of Proton-M booster with three GLONASS satellites in July 2, 2013.

An investigation found out that an upside down installation of sensors sent the rocket plummeting back to Earth.

It was discovered that three sensors had been practically 'hammered' into the wrong position, which led to a loss of $1.3 billion worth of rocket and satellites.