A special D.C. police panel concluded a three-month investigation yesterday into charges of incompetence brought by homicide detectives against their former cheif, Deputy Police Cheif William Trussell.

The panel is expected to turn its findings over to Police Chief Burtell M. Jefferson today.Jefferson is expected to forward the report with his Barry Early next week before its results are made public.

Sources close to the investigation said yesterday that the report, which took several weeks loner than expected, may include a minority opinion offered by Police Deputy Counsel Richard Brooks, a civilian member of the three-man panel.

Brooks has also reportedly objected to a recommendation by the panel in late May that Trussell be temporarily reassigned until the investigation ended.

Brooks and the panel's other two members, Assistant Chiefs Maurice Turner and Marty Tapscott, have declined to comment on their investigation or its results.

Trussell, a 30-year veteran of the force and until late May commander of the plainclothes Criminal Investigations Division, was the focus of an unprecedented revolt in early May by homicide squad detectives who publicly charged him with incompetence and alleged he made a racist remark.

After an extraordinary three-hour meeting with the dissident detectives on May 7, Jefferson appointed the panel. Jefferson's initial handling of the issue strained his relations with Mayor Marion Barry, who was reported unhappy with the cheifs failure to defuse the issue promptly.

The homicide detectives in May gave Jefferson more than two dozen specific instances where they felt Trussell -- whose command included homicide, robbery, burglary and other investigate squads -- had jeopardized major cases since he took over the division in September 1978.

The detectives also allegate that Trussell made a racist remark equating blacks with animals. After a three-week investigation, the panel found that Trussell had made a remark that Jefferson said "damages . . . the public confidence in the department."

Trussell was temporarily transferred to the Field Inspections Division and was officially reprimanded by Jefferson.

High-ranking police officials say they feel the panel's final decision is more difficult. A finding against Trussell could encourage other officers to complain publicly against their superiors, while a favorable ruling for Trussell would exacerbate morale problems within the department.

"What the situation calls for is a Solomon-like decision," one police official said.