WEST PALM BEACH, Fla. -

A South Florida doctor whose license was previously suspended is facing two counts of first-degree murder for the overdose deaths of two patients.

The Florida Department of Law Enforcement said Friday that 61-year-old John Christensen illegally prescribed the two victims oxycodone and other drugs. Christensen operated medical offices in West Palm Beach, Port St. Lucie and Daytona Beach.

A judge Friday ordered Christensen held without bail. His lawyer says Christensen should be presumed innocent.

Also charged in the case is a second physician, Stewart Fox. He is charged with conspiracy to traffic in oxycodone, unlawful prescriptions and other charges. Christensen also faces similar drug-related charges.

Authorities have been investigating the two doctors since January 2011. FDLE says agents reviewed 35 overdose deaths connected to Christensen's clinics.