No, it would be difficult to envision a situation in which gas gangrene would persist for a year without becoming worse. In studies that look at the outcomes of gas gangrene, it is virtually 100% fatal if persons in whom proper care is delayed. It is possible that there has been a different infection for a long period of time that has only recently become more complicated and gangrenous.
I'm sorry, but the clarification did not go through. What further clarification would be helpful?
First, lets clarify some terms. Gangrene can be used to describe two different processes. In some people there can be poor blood supply to a portion of the body (commonly the foot, but can be elsewhere), which over time can cause death of tissue. This condition is sometimes referred to as dry gangrene. There also is an infection of tissue (also frequently involving the foot, but can be elsewhere) involving certain germs that are growing in tissue causing death to the tissue. This condition is called gas gangrene or wet gangrene. This is the type of gangrene that would be associated with infection. The former condition can last for a fairly long period of time, so could have been present for a year. If he had an infectious gangrene, it could not have been present for a year. A lay person, such as the police officer, may have confused the two conditions.
There is no direct study that tries to determine how long someone will survive with a gangrenous infection of the foot without appropriate treatment, as that would be unethical, but a gas gangrene infection is highly lethal if not treated appropriately. here are studies that look at the time period before a person presents for care, but it is impossible to know when the process progressed to the point that it would be considered gangrene. Even with that limitation, the majority of patients present within 24 hours and the longest period of time before presentation was 6 weeks.
Therefore, it would be impossible for there to be a gangrenous infection of the foot for a year, but it is possible that dry gangrene was present for a longer period of time and the police officer did not know to make the distinction.