A former employee of a Baltimore drug abuse program was indicted Thursday on charges that he hacked into office computers and caused a pornographic image to be displayed during a PowerPoint presentation his boss was giving to the board of directors.

Walter Powell, 51, who lives on Frankford Avenue in Northeast Baltimore, is charged with several counts of unauthorized access to computers and unauthorized possession of pass codes. He faces up to 48 years in state prison if convicted on all counts.

Powell, who worked for Baltimore Substance Abuse Systems Inc., surrendered at the Central Booking and Intake Center on Thursday and has a bail hearing scheduled for Friday. He's also facing federal charges of illegally possessing gun silencers, which were filed after city police said they found the devices when they raided his house in connection with the computer investigation.

The indictment announced by the city state's attorney's office is the first to be brought by its forensic investigation unit and was conducted with the Baltimore Police Department's cyber and electronic crimes division.

Baltimore prosecutors said Powell had been director of the company's management information systems until he left in September 2009 after the meeting had been held. The independent company distributes public money to more than 50 substance abuse programs in Baltimore that serve 21,000 people each year.

Greg Warren, the chief executive officer, said that his computers store client files and other personal and medical information on thousands of people. He said after the breach was discovered, he hired an outside consulting firm and determined that "we have no evidence that any patient information was released in any way."

Warren said the cyber attack cost the company $80,000, most of it to rebuild software and implement new security measures.

Authorities said in a statement that Powell became disgruntled, and in the weeks leading up to his departure he used his home computer to gain access to the company's internal servers. Prosecutors allege in the indictment that he installed software that allowed him to track the computer keystrokes of his colleagues.

"Over the course of 32 days, Powell accessed, or attempted to access, the BSAS network more than 100 times using the passwords of those employees," the state's attorney's office said in a statement.

Prosecutors said that Powell broke into Warren's account, forwarded confidential e-mails to employees and "composed a fictitious e-mail message" sent out on a mass distribution list.

The board of directors consists of 25 members who include people in recovery, foundation heads and the city's police commissioner, state's attorney and other city leaders. It's chaired by the Baltimore health commissioner.

Warren said 17 board members were present when his PowerPoint presentation — designed to highlight his accomplishments during what were then his first few months as CEO — got under way. He said his computer shut down and then restarted, projecting the image of a naked woman on two wall-mounted screens — one 64 inches wide, the other 32 inches wide.

Police Commissioner Frederick H. Bealefeld III and State's Attorney Patricia C. Jessamy were not present at that meeting, Warren said.

peter.hermann@baltsun.com