DALLAS — An ongoing audit of Dallas police crime data found that the data missing from the city’s computer database is almost triple the initial estimate, city officials said Monday.

About 15 terabytes of police data are missing besides the 7.5 terabytes initially thought to be lost., city spokeswoman Janella Newsome said.

“The City continues to assess the impact of the compromise on its operations, whether data recovery specialists can recover data from the physical devices on which it had been stored or other systems, and whether any additional systems citywide have been affected,” Newsome told The Dallas Morning News. “As the City continues this audit, it may find additional files are missing.”

City officials ordered the audit after Dallas County prosecutors learned that a city information technician inadvertently deleted 22 terabytes of crime data. Technicians recovered 14 terabytes, but about 7.5 terabytes were likely lost forever. Most modern personal computers can hold half a terabyte to one or two terabytes.

City information technology officials became aware of a massive loss of data on criminal cases on April 5. The police and city IT departments did not reveal it to the district attorney’s office until earlier this month after prosecutors inquired why they could not find computer files on pending cases.

The lost data included images, video, audio, case notes and other information gathered by police officers and detectives, according to a Dallas Police Department statement. A city IT employee was migrating the files, which had not been accessed for the previous six to 18 months, from an online, cloud-based archive to a server at the city’s data center.

“While performing the data migration, the employee failed to follow proper, established procedures, resulting in the deletion of the data files,” according to the police statement.

The IT employee was fired Friday, according to an email sent to City Council members from Elizabeth Reich, the city’s chief financial officer. That employee’s identity has not been made public.

At least one murder trial has been postponed indefinitely and the suspect released on bond because of lost data.