There is a funny ghost film with such a plot. A uncle Biao was killed and turned into a ghost. He wanted to go to heaven, saying that he had to find a murderer to get there.

It was Stephen Chow's brother who hit a ghost.

Dong Piao and Feng Cuifan are police partners. In an operation to catch drug dealers, Feng Cuifan did not arrive at the scene for some reason. Dong Piao single-handedly launched a fierce gun battle with several drug dealers. He was killed, but he never saw the murderer's face until his death. Dong Piao died unsatisfied and vowed to find the murderer. His ghost also floated on the earth. Stephen Chow is a policeman who just graduated from the police academy. Dong Piao wanted him to avenge himself, so he secretly arranged for him to partner with Feng Cuifan and let him live in his former dormitory, which is also next door to Feng Cuifan. Stephen Chow met Vivian, Feng Cuifan's daughter, and was attracted by her beauty. At this moment, Dong Piao appeared, and promised Stephen Chow to help him find out the real murderer and let Stephen Chow win the beauty. Stephen Chow reluctantly agreed. Zhou and Dong soon found the real murderer who killed Dong, but the man was surrounded by many thugs and protected by the mage. No matter who or what, they can't do it. Seeing that Dong Piao's days are numbered, how can they bring the criminals to justice? Uncle Biao investigated the drug-making case, but he died tragically under the gun of the drug dealer Deng Gongzi, and even made a suicide fake, which made Uncle Biao unable to go to heaven. Uncle Biao turns into a ghost and goes back to the police station, hoping to find out the murderer with the help of Officer A Xing (Stephen Chow). A Xing, the daughter of her boss, agreed to help Uncle Biao investigate the real murderer. Seeing that things were exposed, Mr. Deng found an evil mage and caught Uncle Biao's soul in the ghost-catching golden coffin. Under the guidance of Mao's ancestor, Mr. Jin and A Xing made a panacea to save their uncles with gold lovers' urine, cat excrement on the altar and big fairy fart. Together, they defeated the evil mage, and A Xing shot Deng Gongzi himself to avenge Uncle Biao, so that Uncle Biao could go to heaven with peace of mind.