Mo. Rev. Stat. § 57.111: May act in adjoining county, when — deemed employee of sending county for purposes of benefits and compensation.

Whenever any sheriff or deputy sheriff of any county in this state is expressly requested, in each instance, by a sheriff of this state to render assistance, such sheriff or deputy shall have the same powers of arrest in such county as he or she has in his or her own jurisdiction. Any sheriff, or deputy sheriff that a responding sheriff sends, of a county responding to a request for assistance in another county of the state shall be deemed an employee of the sending sheriff's office and shall be subject to the workers' compensation, overtime, and expense reimbursement provisions provided to him or her as an employee of the sending sheriff's office.