The top ranks of the Prince George's County Police Department will undergo extensive reorganization as a result of the appointment of a black civilian police employe to a high-level job in the department, according to police officials.

The black, Thomas M. Davis, will become a lieutenant colonel in the department on July 1. At that time, each of the three current lieutenant colonels will lose some authority so that Davis will have an area of responsibility. The rank of lieutenant colonel is the highest in the department next to that of Police Chief John E. McHale.

Despite their loss of authority, two of the lieutenant colonels -- Joseph D. Vasco and Vincent DuCullier -- will become deputy chiefs in an expansion of that position. The third lieutenant colonel, Rice Turner, already has that title, and is currently the number two man in the department. Davis also will be a deputy chief.

Under the reorganization, Turner will continue to function as the ranking deputy chief with the most responsibility. Turner will be in charge of the department's 600 uniformed officers, who make up 80 percent of the Police Department.

Currently, Vasco is in charge of the uniformed officers as well as the detectives, who do homicide, rape, robbery and drug investigations. When the reorganization take effect, Vasco will have responsibility only over the 100 detectives.

"When I was asked if I wanted to leave this position by the chief, I said no," said Vasco. "I will miss it."

Vasco is generally well liked by the rank and file, while their new boss, Turner, is not. Turner has the reputation of a strict disciplinarian, which he acquired about 10 years ago as head of the internal affairs unit -- the that investigates complaints against police officers.

As a result of the reorganization, DuCullier, who now is in charge of personnel, records, data processing and purchasing, will lose his authority over personnel, including recruiting, to Davis.

Under the reorganization plan, all four deputy chiefs will have equal access to McHale. Previously, Turner reported to McHale, while Vasco and DuCullier reported to Turner. t

McHale said yesterday the reorganization "will give me a broader field of people bringing their experiences directly to me rather than filtering them through other people."