Matthew Thorne was the brother of gangster Rupert Thorne, and a close friend and colleague of Thomas Wayne and Leslie Thompkins.
History
In medical school, Matthew, Leslie, and Thomas were best friends, known as “The Three Musketeers."
Matthew's career took a downward turn when his brother, Rupert, received a gunshot wound and came to his brother for help. Trying to shield him, Matthew did not report the injury to the police, committing a breach of ethics that cost him his license and his professional standing.
Matthew not particularly happy working with his brother.
Matthew was reduced to working secretly for his brother's criminal organization, providing various illegal services to Rupert and his men off the books. Rupert tried to keep his brother happy by setting him up in an unofficial clinic, with his own staff, and various stolen pieces of advanced medical equipment. Inside, however, Matthew yearned for his old life back, and Rupert kept him on the hook with unfulfilled promises to pull strings and reinstate his license.
When Rupert needed open heart surgery, he refused to be admitted to a hospital, where he would be vulnerable to his many enemies. He insisted that his brother do the surgery, but Matthew said that the surgery was beyond his skills and that he could not do alone. He said that in order to succeed he would need the help of another doctor to assist him. To this end, Rupert Thorne allowed his brother to use some of thugs from his organization to kidnap the required specialist. Subsequently, Thorne's men and Doctor Thorne kidnapped Leslie Thompkins from her office. Leslie and Matthew successfully performed the surgery in Matt's "clinic."
Thorne had given orders that Leslie was to be eliminated after the job was done. Hearing this, Matthew renounced all loyalty to his brother. Matthew pretended to go along with the order, but drugged the enforcer with a sedative. Matthew and Leslie quickly made their escape. They were pursued by Thorne's thugs, and nearly killed, but Batman saved them.
Matthew was then arrested as an accomplice to Rupert's gang. While he was awaiting trial, Bruce Wayne visited him in jail, offering to pay for a lawyer and try to convince the judge to be lenient. Suspicious, Matthew was sure that Bruce wanted something in return. When Bruce admitted that he did, it was something Matthew could give happily: stories about his old friend, Bruce's father.