The New York City medical examiner’s office said Thursday that it had discovered more than 50 cases in which it failed to upload critical DNA evidence samples from crime scenes to the state’s DNA database, preventing those samples from being compared to genetic material from convicted offenders.

The error was found during an extensive review undertaken after the office learned that one of its laboratory technicians had missed detecting DNA evidence in at least 26 rape cases — an embarrassing oversight for an agency at the forefront of forensic technology, but one that the office said at the time was isolated and unprecedented.

The new discovery has led to the firing of the office’s deputy director of quality assurance in the lab and the suspension of the director of the office’s department of forensic biology, Dr. Mechthild Prinz.

The suspension of Dr. Prinz was made “pending further review of her management practices,” according to a statement from Ellen Borakove, a spokeswoman for the medical examiner’s office. The name of the deputy director could not be immediately determined.