legal ground
Article 91 of the Criminal Procedure Law If a public security organ deems it necessary to arrest a detained person, it shall, within three days after detention, submit it to the people's procuratorate for examination and approval. Under special circumstances, the approval time can be extended by one to four days. For major suspects who commit crimes on the run, commit crimes many times or commit crimes in collusion, the time for submitting for examination and approval may be extended to 30 days. The people's procuratorate shall, within seven days after receiving the approval letter from the public security organ, make a decision on whether to approve or disapprove the arrest. If the people's procuratorate does not approve the arrest, the public security organ shall immediately release it after receiving the notice and promptly notify the people's procuratorate to execute it. Those who need to continue the investigation and meet the conditions of obtaining a guarantor pending trial or residential surveillance shall be granted a guarantor pending trial or residential surveillance according to law.