Russian investigators have told the mother of Alexei Navalny that she must agree to hold a secret funeral for her son or they will bury him at the prison where he died last week, the late activist's spokeswoman said Friday."An investigator called Alexei's mother an hour ago and gave her an ultimatum: either she agrees to a secret funeral without a public farewell within 3 hours or Alexei will be buried in the penal colony," Navalny's spokeswoman Kira Yarmysh said.Lyudmila Navalnaya refused, arguing that investigators have no authority to decide where and how to bury her son, and demanded to hand over his body by tomorrow, Saturday, Yarmysh wrote on X (formerly Twitter)."She insists that the authorities allow the funeral and memorial service to take place according to traditions," the spokeswoman added.Navalnaya's lawyer submitted an appeal to Russia's Investigative Committee, which probes major crimes, calling on the law enforcement body to launch an investigation and press criminal charges of "desecrating a dead body" against the officials refusing to hand over her son's body. The news comes a day after the late activist's mother said investigators had finally allowed her to see Navalny's body but were pressuring her to hold a funeral for him in secret.Putin's most vocal critic died last week in an Arctic prison where he was being held on charges widely seen as retribution for his anti-Kremlin political activities.Navalny's allies announced Friday that they are offering a reward of 20,000 euros ($21,640) and help fleeing Russia for any information about the circumstances of his death in prison.