``The criminal was detained and arrested red-handed'' refers to the person who committed the crime being arrested by the police and detained. Detention refers to placing a criminal suspect under the control of law enforcement agencies such as the police, and keeping them in custody for a certain period of time for investigation or trial. Red-handed means that the person was arrested immediately after or at the scene of committing the crime, indicating that the crime is still being committed or has just been committed. If a criminal is caught red-handed, the police can immediately arrest the criminal based on witness testimony and physical evidence, and prevent the criminal act.