Deceased Russian dissident Alexei Navalny’s widow is promising to continue his fight against Russian president Vladimir Putin’s regime.

Yulia Navalnaya said in a video message she would continue her husband’s work and accused Putin of playing a role in her husband’s death.

“Putin killed the father of my children. Putin took away the most precious thing I had, the closest and most beloved person,” Navalnya said.

“We know why Putin killed Alexei three days ago, we will tell you about it soon,” she continued. “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.”

Russian authorities announced Navalny’s death in prison Friday, saying only that the 47-year-old began feeling uneasy after a walk and passed away a short time later. A spokesperson for Navalny said Saturday he was “murdered” and confirmed his family was notified of his death.

Navalny had been serving a lengthy prison sentence in an Arctic penal colony on charges widely believed to be political in nature. In December, Navalny went missing after a serious health incident and his lawyers were prevented from accessing a video feed of legal proceedings inside the prison where Navalny was being held, his spokesperson said.

President Joe Biden addressed Navalny’s death in a speech Friday afternoon and attributed it to Putin.

“As people in Russia and around the world are mourning Navalny today, because he was so many things that Putin was not. He was brave, he was principled, he was dedicated to building a Russia where the rule of law existed and it applied to everybody,” Biden stated.