"We have appealed the decision of the Moscow Basmanny Court to issue an arrest warrant, as we believe the decision contradicts the criminal code," Yevgeny Martynov said, adding that the decision was groundless and unmotivated.
Askarova was arrested last Friday while Alexei Frenkel, a suspected paymaster in the killing four months ago of CBR Deputy Chairman Andrei Kozlov, was detained last Thursday, and his arrest was sanctioned by a Moscow court Monday.
The banking regulator, 41, was gunned down in a contract-style killing on September 13. As the Central Bank official in charge of licensing, he closed down many privately-owned banks in an effort to stamp out money laundering and other criminal practices in the sector.
Frenkel's lawyer, Igor Trunov, said earlier that Askerova had blamed Frenkel for involvement in the murder during her questioning.
"Askerova's questioning is the only evidence the Prosecutor General's Office has," Trunov said.
Kozlov was in charge of bank licensing and closed down VIP Bank, where Frenkel held a top executive position, over alleged money laundering three months before his killing. Frenkel's lawyer has not confirmed his client's former top position in the bank.