You can write letters to your family. If the party concerned is detained in a detention center, he shall be criminally detained or arrested on suspicion of committing a crime. In current judicial practice, parties detained in detention centers on suspicion of crimes can communicate with their families, and parties can also write letters to their families. However, the content of the letter must generally be reviewed by the detention center. The content of the letter cannot involve specific cases, cannot affect the trial of the case, and cannot affect the detention center's supervision of the parties. In addition, if the client has a lawyer to defend him, he can also request his family members to appoint a defense lawyer through a letter, and the family members will go through the appointment procedures with the law firm on their behalf and appoint a defense lawyer for the client.