Ross Ulbricht
Ross Ulbricht, 30, started and operated the Silk Road before walking away, defense attorneys said.

Six people fatally overdosed on drugs they purchased from the online drug market the Silk Road, according to evidence prosecutors plan to introduce at a sentencing hearing next month for the site's founder, Ross Ulbricht. Ulbricht was found guilty in February of selling narcotics and operating a continuing criminal enterprise as well as on five other charges.

Ulbricht faces a mandatory minimum sentence of 30 years in prison, though multiple charges carry a possible life term. His attorney, Joshua Dratel, submitted a court filing Friday requesting that the sentencing hearing be pushed back from May 15 in response to the government's plan to introduce evidence that at least six buyers who purchased drugs from the Silk Road died after taking them. Another court filing unearthed by Ars Technica also reveals that parents of two of those buyers will likely testify at the sentencing hearing.

But crucial evidence about the buyers' death has not been introduced, according to Dratel, including “evidence that certain drugs alleged to have caused or contributed to the purported overdoses were purchased on the Silk Road website; medical records relating to underlying and/or pre-existing conditions suffered by certain individuals at the time of their alleged overdoses” and “autopsy reports and toxicology reports related to the deaths of two of the individuals, including the types and quantities of drugs found in each individual's body post-mortem,” among others.

Dratel called the evidence “woefully incompetent” and requested a month delay.

The Silk Road, which was online from February 2011 until October 2013, operated like an Amazon or eBay for illegal drugs, connecting buyers and sellers around the world. It was only accessible with the anonymous Tor Internet browser and reaped $1.2 billion in revenue, according to prosecutors.