(2) Process may be served by a sergeant at arms of either house when the Legislative Assembly is in session or by a person authorized to serve summons and in the manner prescribed for the service of a summons upon a defendant in a civil action in a circuit court. The process shall be returned to the authority issuing it within 10 days after its delivery to the person for service, with proof of service as for summons or that the person cannot be found. When served outside of the county in which the process originated, the process may be returned by mail. The person to whom the process is delivered shall indorse thereon the date of delivery. [Formerly 171.076; 1973 c.827 §21; 1977 c.877 §16; 1979 c.284 §117]