Who are the Russians who allegedly hacked Yahoo?

Moscow (CNN)Dmitry Dokuchaev -- an officer with Russia's intelligence agency, the Federal Security Service -- is one of several men named in the US Justice Department's indictment in connection with a conspiracy to hack into Yahoo's network.

But it seems he is already behind bars -- in the high-security Lefortovo Prison in Moscow. A man by the name of Dmitry Dokuchaev, along with three others, was arrested in Moscow in December. All four are accused of treason, "on behalf of the United States" according to a lawyer involved in the case.
Lefortovo, a grim complex of beige stone surrounded by high concrete walls, is not far from the Moscow Criminal Court, where the four men will eventually face trial.
    An FBI wanted poster for Dmitry  Dokuchaev at a news conference at the US Department of Justice on March 15.
    According to the US Justice Department, Dokuchaev worked for the FSB's Center for Information Security, also known as Center 18. So did the man arrested in December. It seems very unlikely there could be two Dokuchaevs of the same age and background, though the Justice Department says it cannot confirm he is the same individual.
    Center 18 investigates cyber and high-technology crimes; it's the Russian government's eyes and ears on hacking.
    Accused hackers Igor Sushchin, left, and Dmitry  Dokuchaev are officers of the Russian Federal Security Service.
    The indictment alleges that Dokuchaev and another FSB officer, Igor Sushchin, "protected, directed, facilitated, and paid their co-conspirators to collect information through computer intrusions in the United States and elsewhere."
    Before he joined the FSB, Dokuchaev had become an expert in hacking -- and had written many articles on the subject, including "how-to" guides. He was a contributor to Hacker magazine - writing one piece called "How to make a good haul," in which he says: "There is a way to wealth -- to start your own business in the web. One-two years and maybe you will be able to save enough to buy a villa by the Mediterranean Sea."
    Along with Dokuchaev, the deputy head of the FSB Center, Sergei Mikhailov, was also arrested in December. According to Russian media, he was marched out of a meeting with a bag over his head. Mikhailov and Dokuchaev were accused of "betraying their oath and working with the CIA," according to Russian news agency Interfax.
    The high-security Lefortovo Prison in Moscow.
    Another arrested was Ruslan Stoyanov, one of Russia's most accomplished cyberexperts. Stoyanov was head of the computer incidents investigation team at Internet security firm Kaspersky Lab. He had worked at the firm since 2012.
    A St. Petersburg lawyer, Ivan Pavlov, is representing one of the defendants. Pavlov has been a defense lawyer in several treason trials and has no doubt of the stakes involved.
    In this case, treason involves spying for the United States, he said.
    "It's very dangerous for all of the participants. Not only defendants and the lawyers but even for the investigators," he told CNN. "It's a very, very dangerous case for journalists, too."
    CNN has obtained documents relating to February court hearings into the case -- which name all four defendants. But Pavlov thinks a full trial, which would be held in secret, is at least a year away.

    Old allegations

    Ostensibly the four men were arrested in connection with allegations that go back seven years. In a brief statement after his arrest, Kaspersky Lab said Stoyanov was "under investigation for a period predating his employment" with the company. That would mean before 2012.
    Stoyanov had previously worked for an Internet security firm called Indrik and for the Ministry of Interior's Moscow Cyber Crime Unit.
    The defense lawyer, Pavlov, is far from satisfied that the old allegations are the real story behind the arrest of the four men.
    "There is an underwater part which everyone knows, and which we will not talk about. Everyone should know this. Including the people who are listening to us," Pavlov told CNN at his St Petersburg office.
    But, he says, until he receives more information from the prosecuting authorities, he won't know why Dokuchaev and the others are really being held.
    "There is no time, no place, no approach, no description of what happened. I can't answer your question also clearly because it is not a clear accusation."
    According to Russian media, the arrests relate to old accusations made by a Russian businessman, Pavel Vrublevsky.
    Pavel Vrublevsk, founder of an online payments company, accused the four men of leaking sensitive information to the United States in 2010.
    Vrublevsky is the founder of an online payments company, ChronoPay. In 2010, he alleged that Mikhailov and others were leaking sensitive information to the United States. The accusations fell on deaf ears; before long Vrublevsky found himself behind bars, in none other than Lefortovo Prison.
    He was convicted of hiring hackers to disrupt the business of a rival, an intrusion that took down the online payments system of Russia's national airline, Aeroflot for several days. One of those who gave evidence against him was the FSB officer Sergei Mikhailov.
    "He was the one who attacked us with the Aeroflot case," Vrublevsky told CNN.
    "As I understand it, he disclosed to unnamed American intelligence agencies government secrets related to the investigation into ChronoPay," Vrublevsky added.

    US-Russian ties mired

    With Russian prosecutors saying nothing, the real reasons for December's arrests may not be clear for many months. Some analysts believe the arrests of the FSB officers may have been timed to avoid the embarrassment of a US indictment against serving Russian intelligence officers.
    The indictment will do nothing to improve US-Russian relations, already mired in other hacking allegations and investigations into contacts between the Trump campaign and Russian officials.
    In her remarks announcing the indictment, acting Assistant Attorney General Mary B. McCord said, "The involvement and direction of FSB officers with law enforcement responsibilities makes this conduct that much more egregious."
    "There are no free passes for foreign state-sponsored criminal behavior," she added.
    A "high-ranking source" in Moscow cited by the Russian news agency TASS responded that "Washington never appealed to the Russian Federation in connection with accusations against Russians in the alleged hacking of the Yahoo site."
    TASS said that according to the source, this case "suggests another attempt to use the topic of 'Russian hackers' in the domestic political struggle in the United States."