One of the “grandpa robbers” found guilty of stealing jewellery worth millions from reality TV star Kim Kardashian has died one month after being convicted, French media have said.

Didier Dubreucq, 69, was diagnosed with lung cancer while in detention prior to going on trial and had been undergoing chemotherapy.

In May, he and seven accomplices were found guilty of the high-profile Paris heist, during which millions of dollars’ worth of jewellery were stolen from Kardashian nearly a decade ago.

Dubreucq denied any involvement in the heist. “It’s a mistaken identity case… I had nothing to do with this,” he told the court during his testimony in April.

Due to chemotherapy, Dubreucq – nicknamed “Blue Eyes” – was absent from the sentencing, but received a seven-year sentence from the judge of which five were suspended.

He did not spend time in prison following the sentencing as he had already spent two years in pre-trial detention.

Three other people were given sentences of up to eight years, mostly suspended, but also did not return to prison because of time already served.

Judge David De Pas said as he delivered the verdict that “the state of health of the main protagonists ethically prohibits incarcerating anyone”.

During the three-week trial, the court heard how Kardashian was bound and had a gun held to her head during the ordeal.

On the day she took the stand, she recalled thinking she “would be shot dead on the bed”.

The thieves – nicknamed the “grandpa robbers” due to the advanced ages of those involved, stole about $10m (£7.5m) of her jewellery, including the engagement ring her then-husband and rapper Kanye West gifted her, which alone was worth $4m (£3m).

“The crime was the most terrifying experience of my life, leaving a lasting impact on me and my family,” Kardashian said in a statement after the verdicts.