You can't.
Article 12 of the Measures for the Administration of Lawyers' Service Fees stipulates that risk agency fees are prohibited in criminal litigation cases, administrative litigation cases, state compensation cases and group litigation cases.
Thirteenth risk agency fees, the law firm shall sign a risk agency fee contract with the client, and stipulate the risk responsibility, charging method, charging amount or proportion that both parties should bear.
The maximum risk agency fee shall not be higher than 30% of the target amount agreed in the charging contract.
Article 14 A law firm shall strictly implement the management measures and charging standards for lawyers' service fees formulated by the competent pricing department in conjunction with the judicial administrative department at the same level.
It can be seen that the case you are talking about is a criminal case, and risk agency cannot be applied. Due to the particularity of risk agency, even if you can apply for risk agency cases, you should charge fees in accordance with the above provisions.
I believe that after reading the above introduction, everyone has a certain understanding of how to solve the legal knowledge of what needs attention. If you still have legal questions in this field, please consult a lawyer, and they will give you professional answers.