Robert Leslie Bellem is more known for his Dan Turner, Hollywood Detective stories, but like other working writers in the pulp era, his works went to print in a variety of magazines. This one was published in the 1941 issue of Fantastic Adventures, which is now in the public domain. From the Magazine:

There was one thing about robot slaves; they couldn't tell a lie-yet this one did, and put Tim Kermit in a murder cell.