The 23-year-old, a student at the Moscow Engineering Physics Institute, had been serving nine years in prison for a drug offence.
He was given an amnesty in exchange for fighting for Russia in Ukraine, according to the Zambian government.
Foreign Minister Stanley Kakubo said last week that after asking for an explanation about how Nyirenda had ended up in Ukraine, “we were informed that Russia allows for prisoners to be provided an opportunity for pardon in exchange for participation in the special military operation”, which is how Russia refers to its war in Ukraine.
Mr Kakubo said the information had come from his Russian counterpart Sergei Lavrov.
The student was sent to the frontline by the Russian mercenary group Wagner, which has been recruiting prisoners.
The group’s head Yevgeny Prigozhin said last month in a Telegram statement that the student had voluntarily joined up before dying “a hero”.
In September, leaked footage showed Mr Prigozhin outlining the rules of fighting, such as no deserting or sexual contact with Ukrainian women, and then giving the prisoners five minutes to decide if they want to sign up.
Ominously, he told the prisoners he would get them out of jail alive but said he could not promise to bring them back alive.
Nyirenda’s body arrived in the capital Lusaka on Sunday and has been handed over to pathologists for examination.
The body will be given to the family for burial after a post-mortem has been completed, family spokesperson Dr Ian Banda said in a statement.
The drugs arrest
Nyirenda was working as a part-time courier when he was arrested in 2020 with a parcel containing drugs, his older sister Muzang’alu Nyirenda told the BBC last month.
“We believe he didn’t know what was in the package he delivered, he told us he didn’t. He would get text messages for pick-ups and instructions on where to deliver them,” she said.
“On one occasion he was stopped by the police and searched and they found drugs in the package. He explained he was working for an online courier and didn’t know about the parcels but he was arrested,” Ms Nyirenda said.
The family, however, always remained hopeful that he would return home safely.
Zambia has taken a neutral position on the Russia-Ukraine war, like many other African countries, but says it condemns any form of war.