Robert Mullen was a Democratic state senator.
[1] On November 3, 1868, he was elected member of the Nevada Senate, representing Nye County.
[2] Mullen's term started the next day and he served in two regular sessions until the next election in November 1872.
[1][2][3] In 1870, he was also appointed to a local committee to ascertain means of facilitating the construction of a railroad in his region of the state.
[4] In 1872, it was reported that Mullen was "about to leave Nevada for the East".