A joint trial of ex-pharmaceutical executive Martin Shkreli and Evan Greebel, his co-defendant in a fraud case and his former lawyer, would present a “serious risk” that Shkreli would not receive a fair trial, a federal judge ruled on Wednesday.

Shkreli, the founder and former CEO of Turing Pharmaceuticals, and Greebel, a former partner with Katten Muchin Rosenman, are accused of working together in a scheme to defraud investors in Retrophin Inc. to pay off investors in two hedge funds that Shkreli also founded, MSMB Capital Management and MSMB Healthcare.