After the company disbanded on June 6, 1836, he was elected to represent Nacogdoches in the House of Representatives of the First Congress of the Republic of Texas. He served from October 3, 1836, to June 13, 1837. In 1836 Sam Houston appointed him to serve as secretary of a commission to treat with the Indians. He later served as district clerk pro tem of the Nacogdoches District, until at least December 20, 1838. Arnold died on July 3, 1839, at his home in Nacogdoches and was buried in Oak Grove Cemetery there. His widow, Selina, was appointed administrator of his estate. In 1936 the state of Texas erected a monument over his grave. On November 17, 1851, Adolphus Sterne introduced a bill for the relief of Arnold's heirs before the Senate of the State of Texas.
31° 36.179, -094° 38.972
Oak Grove Cemetery