He was born the 5th of March 1803 at Diernæsgaard in Lild sogn. He was tenant of a Kærup Parsonage in Tømmerby. The 16th of December 1836 he married his housekeeper Helene Pedersdatter in Tømmerby Church. She was born in 1813. Casper J. P. L. Diernæs and Helene Pedersdatter got the twins Christian Peter Caspersen and Lars Christian Caspersen in 1838, and in 1842 a daughter Sophie Karen Kirstine Marie Caspersen short before Casper J. P. L. Diernæs' death.
In 1840 only one of the twin boys was at home. The other one, Lars Christian Caspersen, was living by his grandmother Mariane Pretzmann in Diernæsgaard.
By the time the daughter was babtized in 1842, Casper J. P. L. Diernæs was no longer tenant of the parsonage, but lived in Rotbølgaard with some family. He had bought the farm Madsbøll in Hjardemål Klit, but he was seriously ill of tuberculosis, and he didn't move to this farm, but to the family in Rotbøllgaard at Kæret. Christian Peter Caspersen came to the family at the inn of Bjerget. Casper J. P. L. Diernæs spent his last days at Diernæsgaard where he died the 12th of August 1842.
His widow Helene Pedersdatter moved with her little girl Sophie Karen Kirstine Marie Caspersen to her parents, she was now owner of Madsbøll.
In 1844 she married Lars Larsen Diernis, a younger brother to her first husband.
Sigrid V. Djernæs - 1999