Tamerlan Eskerkhanov, Shagid Gubashev and Ramzan Bakhayev (L to R), detained over the killing of Boris Nemtsov, hide their faces inside a defendants' cage at a court building in Moscow, March 8, 2015. [Photo/Agencies]

Kadyrov is widely criticized by human rights groups for violence against dissidents, including abducting and killing them. Dadaev, one of the suspects charged Sunday, had been an officer in the Chechen police troops, reports cited the head of the security council in neighboring Ingushetia as saying.

Kadyrov on Sunday said on Instagram that Dadaev had left the police troops under unclear circumstances. He described him as a "deeply religious man" offended by Nemtsov's comments after the attack on the French satirical publication Charlie Hebdo. Russia's Investigative Committee had suggested Islamic extremism as a possible motive for Nemtsov's killing.

He also praised a man called Beslan Shavanov as a "brave warrior." That was the name given in the unsourced reports of the suspect who allegedly killed himself in Grozny. Kadyrov's post did not give details, but said Shavanov "perished the previous day during an attempt to detain him."

Dadaev and the Gubashevs were arrested in Ingushetia on Saturday, and the other two suspects in suburban Moscow before dawn on Sunday, officials said.

Law enforcement officials have asserted the guilt of all five, but have not released any details of how they allegedly were involved in the killing of Nemtsov.

The 55-year-old Nemtsov, a former deputy prime minister who became one of Putin's most outspoken detractors, was killed a few hours after he had made a radio appearance denouncing Putin for "mad, aggressive" policies in Ukraine.

Nemtsov was working on a report detailing Russian involvement in the war between pro-Russia separatist rebels and Ukrainian forces, associates said.

Nemtsov's killing shocked Russia's already beleaguered and marginalized opposition supporters.

Russia's top investigative body said it was considering several possible motives, including connections to Islamic extremism and Nemtsov's personal life.