1, did the other person die in a car accident?
2. According to the provisions of Article 133 of the Criminal Law, whoever violates traffic management, thus causing a major accident, causing serious injury or death or causing heavy losses to public or private property, shall be sentenced to fixed-term imprisonment of not more than three years or criminal detention; Whoever escapes after a traffic accident or has other particularly bad circumstances shall be sentenced to fixed-term imprisonment of not less than three years but not more than seven years; Whoever escapes and causes death shall be sentenced to fixed-term imprisonment of not less than seven years. According to the regulations, your friend is suspected of traffic accident. Of course, the police have the right to detain and arrest, and you can also apply for bail for your friend.
3, you can hire a lawyer to represent you, which is more professional.
Personal opinion, for reference only.