From Portrait & Biographical Record of Tazewell and Mason Counties 1894
p.671:

LEONHARD HEISEL. Among the prominent business men of Tazewell County who attained to the highest round on the ladder of success, and were counted among its worthy and honored citizens, may be mentioned Leonhard Heisel. No name may be more properly placed in the history of the county than his, for he was not only one of the most successful and popular business men, but was of such a social and genial nature, that he made many friends. He was one of the oldest settlers of the county and engaged for many years as a merchant, and later in the insurance business in Pekin, where he was classed among its wealthiest citizens.

Our subject was born in Hesse-Darmstadt, Germany, March 26, 1819. He was the son of John Heisel, a native of Germany, and a farmer and weaver. He was an active member of the Lutheran Church, and died in his native land when sixty-four years of age. His wife, Mrs. Elizabeth (Karg) Heisel, was also a German by birth, and reared a family of eight children, only two of whom are living.

Leonhard was the fifth in order of birth in the family, and attended the schools of Germany until reaching his fourteenth year, when he helped his father in his business, and later learned the tailor's trade. In 1842 he began to do journeyman work, traveling through Baden, Prussia and Wurtemberg. Four years later, at Graefeldt-on-the-Rhine, a silk manufacturing town, he married Miss Mary Charlotte Wilhelmina Saur, who was born in Berlin.

In 1848, Mr. Heisel decided to come to America and left Antwerp on a vessel which forty-two days later landed him in New York City. Thence he went to Albany, and after a stay there of three weeks, came to Pekin by way of canal and river, when this now prosperous city contained but six hundred inhabitants. He immediately opened up a merchant tailoring establishment, which he carried on for four years, then engaged in the grocery business, and later became a dry-goods merchant. His first partner in the latter trade was Mr. Reuling, his second Mr. Steinmetz, and the last gentleman with whom he did business was C. A. Becker. He was very successful as a merchant, and had one of the finest establishments in the city until 1881, when he sold out. A few months later he took the agency for many of the principal insurance companies.

From the time Mr. Heisel came to this city in 1848, nearly everything he touched turned to money, and he was one of the substantial men of the county. He built several business houses in the city, owned three brick stores, and considerable valuable residence property. His good wife departed this life May 22, 1884, after having become the mother of eight children, of whom five are living: Rudolph, living in Terre Haute, Ind.; Henry, a hardware merchant of Stillwater, Minn.; Martin, a prominent grocer of this city; and Elizabeth and Mary, at home. Socially, Mr. Heisel had been a Mason since 1851, and was Treasurer of the lodge for over a quarter of a century of the order in Pekin. He also belonged to the Turner society, and in politics was a strong Democrat. His death, December 15, 1898, was mourned by the citizens of Pekin, with whose interests in his own had so long been identified.