If nothing is done, the maximum sentence is three years. You should keep the contract before the settlement, otherwise it is impossible if someone accuses you of kidnapping. The crime of kidnapping begins at 10.
The previous lawsuit was a civil dispute. Although it is decided, it is not the final judgment. You can further appeal to a higher court.
Your fourth uncle is now committing a criminal case, and the trial is held in a criminal court. Previous debt disputes will only be used for reference and will not be acquitted. The urgent task is how to get your fourth uncle to reduce his punishment or get a suspended sentence: social affairs now cost money. If you want to find someone, you can only go to the police station or the court, and it is useless to find a procuratorate.
I'll tell you the procedure of this case: within one month from the first day of detention, the case is in the public security bureau, and then go to the public security bureau. If it is useful, they can directly not sue your fourth uncle. A month later, the procuratorate took over, and they were only responsible for reviewing the authenticity of the case. It's no use finding them. You have to go directly to the court to find a relationship. If he goes to court, the fourth uncle will definitely be punished lightly or heavily. The good ones are sentenced to six months' criminal detention or probation, and the bad ones are sentenced to no more than three years.