Authorities in Russia have made 5 arrests... in the ongoing investigation into the murder of Boris Nemtsov -- an outspoken critic of the Kremlin.
With more, we turn to Paul Yi at the news center.
Paul, authorities are calling it a "contract killing"... allegedly carried out by these men.
Any details released on their backgrounds?

All five suspects are said to be Chechen... from Russia's predominately Muslim Northern Caucuses.
Two of them, including an ex-policeman, have been charged with murder by a Moscow court.
However, Nemtsov's closest allies are rejecting the narrative that his death was the result of religious extremism, but rather a politically motivated terror attack.
Arirang's Connie Kim reports.
A Moscow court has charged two men accused of plotting to kill Russian opposition leader Boris Nemtsov, an outspoken Kremlin critic.
Zaur Dadayev, a former police officer who fought Islamic insurgents, admitted he was involved in the killing, while the second suspect, Anzor Gubashev, pleaded innocent.
Russian state television showed the men's arrival in court, wearing handcuffs and covering their faces.
Three other suspects have been jailed.
All five men are of Chechen origin, which could potentially be a sensitive issue in Russia, as many Russians view Chechens as violent extremists.
A sixth suspect reportedly blew himself up with a grenade in a standoff with police in the Chechen capital of Grozny.

Nemtsov was assassinated in late February, days before he was set to address a major anti-government rally.
He was also to publish a report on the Russian military's involvement in the war in Ukraine, despite Moscow's denial that it has supplied separatists with troops and weapons.

The biggest question now is who ordered Nemtsov's assassination.
Some of his supporters have gone so far as to say the Russian government was behind the killing.
Russian officials deny that, and President Vladimir Putin has condemned the killing and pledged to do everything to find a