Yulia Navalnaya, wife of late Russian opposition leader Alexei Navalny, accused Russian President Vladimir Putin of being involved in her husband's death and vowed on Monday to continue his work.
"We know why Putin killed Alexei three days ago, we will tell you about it soon," she said in a video message. "But the main thing we can do for Alexei and for ourselves is to continue to fight. I will continue the work of Alexei Navalny, continue to fight for our country, and I urge you to stand next to me."
Navalny, a long-time Russian opposition politician and critic of the Kremlin and Russian President Vladimir Putin died in prison at age 47 on Friday, the state prison service said.
Kremlin spokesman Dmitry Peskov had earlier denied any involvement in the death, saying there were "no statement from doctors, no information from forensic experts, no final information from the Federal Penitentiary Service, no information about the causes of death."
Officials at a morgue in the Arctic city where it's believed Navalny's body is likely being held refused on Monday morning to allow his elderly mother and lawyers in, according to Navalny's team.
MORE: Alexei Navalny's allies accuse Russian authorities of deliberately withholding his bodyThe officials also refused to say whether Navalny's body was there, according to Navalny's team.
Russia's Investigative Committee, which often handles political cases, has also informed his relatives that the examination of his death has been "extended" -- meaning they will not hand the body over for now, according to Navalny spokeswoman Kyra Yarmysh.
Navalny's team later said his body would be held by officials for 14 days, while testing is underway.
Navalny's team have said they believe Navalny was murdered and have accused Russian authorities of now withholding his body to conceal evidence of how he died.
"They lie, buy time for themselves and do not even hide it," Yarmysh wrote on X.
Navalnaya was expected to address a meeting of the European foreign ministers' meeting in Brussels on Monday.
ABC News' Jon Haworth and Nadine El-Bawab contributed to this story.