Alexei Navalny's mother asked local police to open a criminal case against the investigators who she says are withholding her son's body, on charges of "abuse of a corpse."
The Russian opposition leader's body was taken to the city of Salekhard, located on the Arctic Circle, after he died in a nearby penal colony on Feb. 16, according to Russian officials.
The appeal claims that the lead investigator into the death of Navalny made threats towards his mother, Lyudmila Navalnaya, and promised to commit illegal actions with Navalny's body in order to prevent his burial.
Navalnaya said in a video message posted to YouTube Thursday that the Russian government is blackmailing her and trying to force her to have a secret funeral for her son.
"So, as one of the arguments, the investigator said, 'time is working against you, because the corpse is decomposing,'" the complaint alleges. "Such words cause irreparable moral harm [to Navalny's mom], grief from the loss of her son is complemented by an absolutely insulting attitude on the part of the investigative authorities and blackmail," the document says.
"It is also important that the investigator said that if the public is informed about what is happening, serious consequences will come for her personally," the complaint says.
The document also says that Navalny was a baptized Orthodox Christian, and he regularly attended church. According to the Orthodox faith, it is customary to bury the body of the deceased on the third day, although eight days have passed since his death.
MORE: Kremlin rejects call for independent postmortem on opposition leader Alexei NavalnyNavalny's team has accused Russian officials of killing the critic of President Vladimir Putin. Navalny was previously poisoned and nearly died in an assassination attempt his supporters blamed on the Russian president.
His cause of death has been listed as "natural" on his medical report, Navalny's spokesperson Kira Yarmysh said this week.
Dmitry Peskov, the Kremlin spokesperson, on Tuesday called the allegation that he was murdered by Russian officials "unfounded" and "unsupported."