Biden investigation

The president nominates the attorney general and the senate approves but the president can fire the attorney general without senate approval. In other words the attorney general, like all federal employees, serves at the pleasure of the president. He may be the chief legal officer for the country but he works for the president. This is important because the Justice Department, which is headed by the attorney general, is about to investigate the son of the president. Some surmise that the investigation could lead to the president himself. Is this a conflict of interest. If you are a judge and your son comes before you in a case you would be asked to recuse yourself. Will this investigation be tainted?