Doctor Turns Himself In to Authorities: David G. Gardner, a neurosurgeon charged in what prosecutors are calling a $4.2-million tax-fraud and money-laundering conspiracy, surrendered to authorities in Los Angeles. Gardner founded Primedex Corp., a health care company that was one of the biggest and most controversial workers’ compensation medical enterprises in Southern California during the late 1980s and early 1990s. He had been considered a fugitive since last week, when the Los Angeles County district attorney’s office filed five felony counts against him. Gardner is being held on $10 million bail. A bail hearing and arraignment are scheduled for Nov. 14.