The U.S. State Department remained tightlipped Monday about claims that Russian opposition leader Alexei Navalny was close to being freed in a prisoner swap when he died.

Why it matters: The Biden administration has held that the Russian government is to blame for Navalny's death, but the circumstances surrounding it remain murky, particularly following the unconfirmed report of the proposed prisoner swap.

Driving the news: Maria Pevchikh, a Navalny ally and the head of investigations at his Anti-Corruption Foundation, posted a video to YouTube Monday claiming Navalny was "killed" because he was close to being freed in a prisoner swap, Reuters reported.

• Pevchikh alleged that there was a proposal to trade Navalny and two unnamed American citizens in exchange for Vadim Krasikov, a Russian hit man imprisoned in Germany.
• Pevchikh did not present documentary evidence in the video. The Kremlin has denied involvement in Navalny's death.

The big picture: State Department spokesman Matthew Miller said at a press briefing Monday that it is the department's policy not to comment on the details of prisoner negotiations.

• "All I will say about this matter is that we have long called for the release of Alexei Navalny, and that was our position on the matter," Miller said.
• Asked about the allegation that Navalny was killed because of a pending prisoner swap, Miller said he didn't have "any comment on that specific assessment."

Zoom out: The Russian penitentiary service said Navalny died after losing consciousness while walking in the Arctic penal colony to which he was relocated in December.

• "Make no mistake, Putin is responsible for Navalny's death. Putin is responsible," President Biden said earlier this month.

Flashback: Krasikov's name was reportedly floated last year in prisoner exchange talks between Russia and Western officials, potentially to secure the release of Wall Street Journal reporter Evan Gershkovich, the WSJ reported.

Go deeper: How Navalny became Putin's biggest political foe