Aides to Aleksei A. Navalny asserted on Monday that the Russian opposition leader had been on the verge of being freed in a prisoner exchange with the West before he died earlier this month.

Western officials were in advanced talks with the Kremlin on a deal that would have released Mr. Navalny along with two Americans in Russian prison, a top aide to the dead opposition leader, Maria Pevchikh, said in a video released on the Navalny team’s YouTube channel.

As part of that deal, Ms. Pevchikh said, Germany would have released Vadim Krasikov, the man convicted of killing a former Chechen separatist fighter in a Berlin park in 2019. Mr. Putin praised Mr. Krasikov in his interview with the former Fox News host Tucker Carlson this month, describing the convicted assassin as having been motivated by “patriotic sentiments.”

Ms. Pevchikh’s assertions about a pending deal could not be independently confirmed. There was no immediate comment from any of the parties reportedly involved in the trade described by Ms. Pevchikh. A Kremlin spokesman did not respond to a request for comment.

“Navalny was supposed to be free in the coming days,” Ms. Pevchikh, the chairwoman of Mr. Navalny’s Anti-Corruption Foundation, said in the video. “I received confirmation that negotiations were at the final stage on the evening of Feb. 15.”

American officials had acknowledged that German officials were asking for Mr. Navalny to be released in any deal that would have freed Mr. Krasikov, though they did not indicate a deal was close. A German government spokeswoman declined to comment when asked about the Navalny team’s assertions at a news conference on Monday.