Liana Askerova, a restaurant owner, is believed to be a link between the paymaster of the September 13 death of Kozlov, who led a crusade against money laundering and other criminal practices in the banking sector, and the contract killers. She was arrested last Friday.
"The Russian Prosecutor General's Office has brought charges against [Liana] Askerova. She is a suspected accessory in the case," an investigation source said.
Askerova gave herself away when she began looking for a lawyer to help the arrested middleman who found the alleged killers, which attracted police attention, popular daily Kommersant said earlier in the week. Investigators' shadowing helped to gather sufficient evidence to detain the woman, who then gave away the paymaster's name.
Alexei Frenkel, who took a top position in the private VIP Bank, was arrested last Thursday and charged Wednesday with ordering the murder of Kozlov.
Kommersant quoted sources close to the investigation as saying that a personal conflict between Kozlov and Frenkel erupted in 2005 when the banking regulator refused to include VIP Bank in the deposit insurance system, and later withdrew the bank's operating license.
Investigators told the paper the infuriated Frenkel then ordered the killing. The banker has denied the accusation.
Seven people have so far been detained in connection with Kozlov's murder, and some have reportedly confessed to having been hired to kill the high-profile banking official.