New revelations have been unveiled about the Cleveland police officer who fatally shot a 12-year-old boy holding a toy gun last month and the police department where he works.

The shooting took place in early November after police received a report about someone possibly holding a toy gun at a local park. Video footage of the incident shows that the victim, Tamir Rice, was walking around and waving a pellet gun outside the Cudell Recreation Center. He eventually sat down on a park bench in the park's gazebo before a cop car pulls up near him. That's when rookie policeman Timothy A. Loehmann, 26, jumped out of the car and opened fire, two seconds after arriving on the scene. The boy then died a lay later, after being transported to the hospital.

Cops were called to the playground after a man who was sitting in a nearby gazebo called 911 to report that he saw someone pointing a gun at people. Although the caller stated several times that the weapon was probably a toy, the dispatcher did not transmit that information to the responding officers. As a result, the officers believed they were looking for an adult black male on a "gun run," said Deputy Chief Ed Tomba at the conference, according to NBC News.

According to records released by police, Loehmann resigned from a previous police job as a patrolman in training back in Dec. 2012, before he was hired by the Cleveland force in May.

A Nov. 2012 memo shows that Loehmann was deemed emotionally unstable and unfit for duty, especially when it came to handling firearms. Deputy Chief Jim Polak also questioned Loehmann's ability to follow instructions and make good decisions under stress.

He cited a report from a firearms instructor who said Loehmann was "distracted," "weepy" and unable to "communicate clear thoughts," during his training. As a result, "his handgun performance was dismal."

The report also said Loehmann was in an "emotional meltdown" due in part to personal problems with his girlfriend.

Polak concluded that Loehmann had shown a "dangerous loss of composure" during live range training and lacked the maturity to be on the force.

"I do not believe time, nor training, will be able to change or correct the deficiencies," he wrote on Nov. 29, four days after Loehmann resigned.

Attorney General Eric Holder also announced on Thursday that results from an ongoing federal investigation into the Cleveland Police had found "unreasonable and unnecessary use of force" by the city's Police Department, reports the New York Times.

The Department of Justice found that the Cleveland police used "unnecessary, excessive or retaliatory use of less lethal force" involving Tasers, chemical spray and fists.

"Cleveland officers are not provided with adequate training, policy guidance, support and supervision," the Justice Department concluded in its report.

"Accountability and legitimacy are essential for communities to trust their police departments, and for there to be genuine collaboration between police and the citizens they serve," Mr. Holder said in a statement. "Although the issues in Cleveland are complex, and the problems longstanding, we have seen in city after city where we have been engaged that meaningful change is possible."