This is the shocking moment police began beating a restrained man who had been stabbed in the head as he lay bleeding in a park.Darren Grace had staggered into Liverpool's Stanley Park in the early hours of Sunday, August 1 when three officers at first came to his aid.However footage shows that as Mr Grace seems to try to resist treatment, one officer rains down a volley of eight punches onto his injured head while a female officer puts her hand on his arm.Five minutes later, just before 8am, both she and the other officer appear to punch Mr Grace in the head and back as he lies face down on the ground.The 31-year-old was later charged with two counts of assaulting a police officer - charges which were eventually dropped when Crown Prosecution Service lawyers saw the tape and realized there wasn't enough evidence 'to provide a realistic prospect of a conviction'.After receiving basic treatment, Mr Grace was held in a cell for 11 hours.Today Merseyside Police accused the Anfield joiner of being violent towards the officers adding 'CCTV images can never show the whole story'.After being shown the tape by the Liverpool Echo, the force voluntarily referred the incident to the Independent Police Complaints Commission.