DOVER, Del. — Criminal charges cannot be brought against four Wilmington police officers involved in the fatal shooting of a man in a wheelchair, although one officer exhibited ‘‘extraordinarily poor’’ police work and should not be allowed to carry a gun in public, the Delaware attorney general’s office concluded in a report released Thursday.

State officials also said their investigation into the September shooting of Jeremy McDole revealed serious deficiencies in the Wilmington police department’s use-of-force policies and training, and in preparing officers to deal with people with mental illness and other disabilities.

‘‘Most significantly, we find that the ‘‘continuum of force’’ provisions of the Wilmington Police Department’s use of force policy are effectively meaningless for police officers as currently written,’’ officials noted in the 31-page report.

Police confronted McDole on Sept. 23 after receiving a 911 call about a man with a gun.

A bystander’s cellphone footage shows officers repeatedly telling McDole to drop his weapon and raise his hands and McDole reaching for his waist before shots erupt.

In court records that predate last year’s shooting, law enforcement officials have stated that McDole, who was shot in the back by an associate in 2005, used his wheelchair to hide things.

Authorities said their investigation into the shooting included interviewing witnesses, officers and McDole’s family members, analysis of ballistics and autopsy results, video evidence, and consultation with two nationally recognized police use-of-force experts.

The attorney general’s office concluded that police were justified in shooting McDole because they believed that deadly force was necessary to protect themselves or others.

Associated Press