Ukrainian investigators have wrapped up an inquiry into two suspects accused of plotting to assassinate President Vladimir Putin after the March presidential election on orders of Chechen rebel leader Doku Umarov.

It was not clear Tuesday when the case against Chechen native Adam Osmayev and Kazakh national Ilya Pyanzin would be sent to court. But Osmayev is reportedly actively cooperating with investigators for fear of extradition to Russia.

The Prosecutor General’s Office asked Ukraine to turn over the men in March, but it appeared Tuesday that the Russians were keeping an eye on the Ukrainian proceedings rather than actively pushing for extradition.

Pyanzin and Osmayev were arrested in the Black Sea port of Odessa on charges of illegal possession of explosives after a Jan. 4 blast at their Odessa apartment building. An associate, Ruslan Madayev, was killed in the blast, which resulted from the mishandling of explosives.

Russian state television broke the news about the Putin assassination plot in late February and showed video footage of Osmayev detailing a plot to bomb Putin’s motorcade in Moscow after the March 4 presidential election. The emergence of the news less than a week before the vote prompted skeptics to speculate that it was a publicity stunt meant to boost Putin’s popularity ratings, while human rights activists voiced worries that the suspects had been tortured and raised doubts that there ever had been a plot against Putin.

At Russia’s request, Osmayev has been on an international wanted list on a number of terrorist charges since 2008.

Osmayev and several associates were briefly detained in Moscow in 2007 in connection with a bomb plot against Chechen leader Ramzan Kadyrov, Kommersant reported Tuesday, citing a source in the Ukrainian Security Service.

Osmayev was released for lack of evidence and fled to Ukraine, where he plotted a bomb attack against Kadyrov in Odessa in July 2011, it said.

In April, Moscow’s Lefortovsky District Court issued an arrest warrant in absentia for the two suspects on five charges: membership in an armed group, illegal production of instruments of crime, attempt on the life of a political leader, illegal production of weapons, and illegal purchase, sale, storage, transportation or carrying of weapons, RIA-Novosti said.

If convicted of the charges, the suspects face up to life in prison.

In Ukraine, the two suspects face 15 years on charges of forming a terrorist group and preparing a terrorist act, Kommersant said. Pyanzin and Osmayev admitted guilt, and Osmayev is cooperating with investigators to avoid extradition to Russia, the report said.