The following bio from "Portrait and Biographical Record of Clinton, Washington, Marion, and Jefferson Counties, Illinois: Containing Biographical Sketches of Prominent and Representative Citizens of the Counties", published in 1894 by Chapman Publishing Co., Chicago.

"Thomas Casey and Harriett Maxey were married October 5, 1819. In fact, there was a triple wedding, which made the occasion one of more than ordinary interest. The other couples were Abraham T. Casey and Vylinda Maxey [Thomas's brother and Harriet's sister], and Bennet N. Maxey and Sallie Overby, the six participants standing at the altar at the same time.

"After his marriage, Mr. Casey began the development of a farm. His home was a little log cabin in the midst of an undeveloped tract of land. Deer could easily be shot and bears were frequently killed in the neighborhood. He entered about 250 acres of land from the Government,and bore all the hardships and trials of pioneer life while performing the arduous task of opening up a farm.

"He and his wife joined the Methodist Church in 1819, and he at once was made a Class-leader and soon became a local preacher. He was untiring in church work and the cause was greatly advanced by his earnest efforts. He gave the ground on which the Pleasant Grove Church was built, aided in the erection of the house of worship, and when it was destroyed by fire, helped to build the brick structure now [1894] in use. The poor and needy found in him a friend, and his neighbors a wise counselor.

"Thomas M. Casey was a farmer and became an extensive breeder and buyer of hogs, cattle, and mules. He was a devout Christian and took much interest in church, the Pleasant Grove neighborhood (4 miles north of Mt. Vernon) having the first place of worship in Jefferson County, and becoming famed all over Southern Illinois as a religious rendezvous. Thomas M. Casey's home was headquarters for the pioneer circuit riders and the wandering evangelists who carried the Bible messages to the dangerous western wilderness.

"He passed from this earthly life October 4, 1868, and was buried at Pleasant Grove. His wife, who shared with him in all religious work, and was a faithful member of the Methodist Church for 57 years, died March 15, 1877."

This website has a lot of information on Thomas Casey.