Aaron Stern knew him personally and writes:
Dr. Leitner was born in 1800 in a town of Hungary. His father, who was a rich man, destined him for the rabbinical chair, but as he preferred the medical profession, he proceeded to Pesth, and there, after eight years study, he received his diploma, and was engaged as a military physician by the Austrian Government. Subsequent events led him to make a voyage to Constantinople, when, quite by accident, in the house of a Jewish friend, he became possessed of the Gospel he had so long coveted, yet dreaded to purchase.
Brought in 1844 as a humble, penitent, and sincere believer to the foot of the mercy-seat, his heart immediately expanded with love and deep compassion toward his Jewish brethren; and, in 1853, after many hindrances and obstacles, he resigned a lucrative position at Broussa, and entered the service of the Society as medical missionary, in which capacity he continued until his removal by death on the 7th of April in the present year (1861). T
horoughly versed in the Bible, and imbued with the Spirit of his Divine Master, he only yearned to make others sharers in those blessings and privileges he so fully knew how to appreciate himself. Often did I hear the suppliant entreaties which he addressed to the crowds who sought his professional skill, that they would not only care for the body, but also seek help and safety in redeeming lover for the immortal soul.
Gidney, W. T. History of the London Society…1908. chapter XXXVIII