Dr Richard Schmidt is being charged with attempted second-degree murder of his girlfriend, a 33-year-old nurse, in a case that is gripping the Louisiana city of Lafayette, where he practised gastroenterology.
According to prosecutors, Dr Schmidt committed the crime in 1994 out of fury at his girlfriend who had been trying in vain to break off their 10-year relationship.
The woman, who has not been identified, had for years been voluntarily accepting injections of vitamins from the doctor to help with fatigue.
Lafayette police allege that Dr Schmidt drew blood from a patient he was treating who had the HIV virus, which causes the disease Aids, and took it to the woman's home.
He told her that the syringe contained Vitamin B12 and urged her to let him perform the injection.
Prosecutors said the woman was in bed at the time and refused to agree to the injection. But the doctor allegedly insisted and injected her against her wishes.
"Before she could do anything more, he jabs her in the left arm," Michael Harson, a US District Attorney, told the court.
"She never even sees the hypodermic. Next thing, he's leaving almost immediately".
The woman, who had no further contact with Dr Schmidt, later underwent a blood test which confirmed that she was carrying the HIV virus.
The charges against Dr Schmidt will be upgraded to second-degree murder if in the meantime she develops Aids and dies.
Lawyers for the doctor insist that he is innocent and that the woman is pursuing a vendetta to bring him down.
During a prison visit, his wife recently declared: "He is a good man. He is not capable of doing this.
"People won't know all the good that he has done, and now this. He is ruined."Reuse content