The Russian Investigative Committee announced the detention of a suspect in the Moscow terrorist attack that killed Lieutenant-General Igor Kirillov and his aide, Ilya Polikarpov, on December 17, Meduza reports.

The suspect, a 1995-born Uzbek citizen, was apprehended in the village of Chernoye in the Balashikha district of Moscow oblast.

According to investigators, he was recruited by Ukrainian intelligence services and promised US$100,000 and relocation to a European country in exchange for carrying out the attack.

Western media reports say Kirillov who was wanted by Ukraine for using chemical munitions was killed by a remotely detonated bomb in Moscow on Tuesday.

Lieutenant-General Igor Kirillov, who headed Russia’s radiological, biological and chemical protections forces, was killed by an explosive device planted in an electric scooter.

Ukraine’s security services were behind the assassination, a source told CNN, calling Kirillov a “war criminal and an absolutely legitimate target.”

This comes a day after Ukrainian prosecutors charged the general in absentia with the use of banned chemical substances in the war on Ukraine.

The United Kingdom will not mourn Igor Kirillov, the Russian general killed in an explosion in Moscow on Tuesday, Downing Street has said, according to CNN.

“Clearly, we are not going to mourn the death of an individual who has propagated an illegal invasion and imposed suffering and death on the Ukrainian people,” UK Prime Minister Keir Starmer’s official spokesperson was cited as saying on Tuesday.

Starmer’s spokesperson added that the UK government has “always been clear that Ukraine has the right to self-defense against Russia’s illegal war.”

“As the prime minister said just yesterday, Russia could put an end to this conflict today. It is Russian aggression that is causing this conflict and the ongoing suffering of the Ukrainian people,” he said.

The UK sanctioned Kirillov in October, saying he was “responsible for helping deploy” chemical weapons on the battlefields of Ukraine.