Ahmad Ahmadi was born in 1885 in Mashhad, Iran, to Mohammad Ali Ahmadi. Details about his early life are scarce. He trained as a nurse and eventually secured employment at Qasr Prison in Tehran. During the reign of Reza Shah Pahlavi, Qasr Prison was notorious for housing political prisoners, many of whom opposed the Shah's policies. Ahmadi's role as a nurse in this environment positioned him in close proximity to these detainees.

In his capacity as a nurse at Qasr Prison, Ahmadi was implicated in the deaths of numerous political prisoners during the 1920s and 1930s. He employed a method of injecting air into the bloodstream of inmates, leading to fatal embolisms. This technique was both clandestine and difficult to detect, making it an effective means of execution without overt signs of foul play. Notable victims included:​

Mirza Mohammad Farrokhi Yazdi: A prominent poet and journalist known for his critical stance against the government.​

Abdolhossein Teymourtash: A former Minister of Court and influential political figure.​

Sardar As'ad Bakhtiari: A leader of the Bakhtiari tribe and constitutional revolutionary.​

Taghi Arani: An intellectual and founder of the Iranian communist movement.​

Ahmadi was reportedly compensated between 10 to 15 Iranian tomans for each execution, with higher-profile targets fetching up to 100 tomans. Following the 1941 Anglo-Soviet invasion of Iran, which led to Reza Shah's abdication, the new government sought to address past injustices. Under the judiciary led by Jalal Abdeh, investigations into the former regime's crimes commenced. Ahmadi was apprehended, tried, and found guilty of multiple murders. He was publicly executed by hanging in October 1944 at Tehran's Toopkhaneh Square.