Russian investigators said on Monday that they identified a second suspect in the murder of Darya Dugina, a strident supporter of the war in Ukraine and daughter of a prominent ally of President Vladimir Putin.
The alleged accomplice in the murder plot was a Ukrainian born in 1978 who entered the country via Estonia on July 30, dpa news agency quoted Russia's Federal Security Service (FSB) as saying.
The FSB named the man and claimed he had helped prepare the crime and then left Russia again.
Dugina, a 29-year-old Russian nationalist commentator who frequently appeared on pro-Kremlin media, died when the car she was driving exploded on the outskirts of Moscow on August 20.
Russia quickly blamed Ukrainian intelligence services for the attack and said they had identified the main suspect: a Ukrainian woman who was said to have rented a flat in Dugina's building to observe her.
The FSB said the woman was born in 1979 and entered Russia at the end of July.
She then departed Russia via Estonia directly after the bombing.
Kiev denies any involvement in the attack.
Most analysts believe her father, ultra-nationalist ideologue Alexander Dugin, was the true target.
International media frequently refer to him as "Putin's brain".