I'm not sure what you want to sue them for--that is, what is the basis of your lawsuit? Do you think that this officer has something against your brother (based on the previous incident you briefly described), and, for that reason failed "to use any type of hostage protocol"? Could it be that the officer's failure to do so has to do with the fact, perhaps, this was not a hostage situation? Simply grabbing someone is not the same as grabbing someone, putting a gun to their head, and threatening to shoot them if his/her demands were not met.
In any case, you can always search for a local civil rights attorney using Avvo's "Find a Lawyer" tool.