After criminal detention, you can be released without writing a letter of understanding.

This also depends on the specific criminal act, if the suspected crime is minor, it is ok. For example, if you are forgiven for the crime of intentional injury, you can find a guarantor, yes, but not necessarily. If the crime is serious, such as being sentenced to more than three years, then bail cannot be granted. If you don't understand anything, you can continue to ask questions or for more details, please visit Weihai lawyer portal: www.wh-lawyer.com; If you think my answer is helpful to you, I hope it can be adopted and praised.