"Lets hope no one gets hurt... its not like there's a decent hospital around here after all." - Albert Lester
History
Dr. Lester was formally the administrator of a hospital located in the Arklay Forest region. At some point his wife, Dorothy Lester, became afflicted with a serious illness. In desperation, Dr. Lester accepted trial drugs from Umbrella and used them on the hospital's patients. These trial drugs were actually developed from the T-virus, and were deliberately being tested with the patients as live test subjects. Al hoped that a cure for his gravely ill wife could be found through this means.
On May 20 1993, Dorothy was administered a T-virus variant known as T-JCCC203. Her condition improved for two days until the virus began to erode and exhibit standard T-virus traits. Eventually, Dorothy became a zombie and sparked an incident which left many of the hospital's patients and staff dead. Among those killed was a Raccoon City reporter named Kurt. The only survivor was Alyssa Ashcroft, a fellow journalist who accompanied him. Consequently, the hospital was shut down and abandoned.
Lester collaborated with Umbrella researcher Greg Mueller, and commisioned him to erase Alyssa's memory of the incident to prevent the truth being reported to the press, which would also likely implicate Umbrella.
Five years following Dorothy's death, Lester retired to a reclusive cabin in the forest. Over these five years he kept returning to the hospital. On one such visit in 1998, Lester encountered a large, monstrous plant in the basement level's intensive care unit. From that day forth, he began to view the plant as the reincarnation of his deceased wife. Over time, Lester began to show signs of insanity and soon enough, began to butcher animals and lead lost hikers in the woods to the hospital in order to feed them to the plant.
Lester was almost certainly infected by the same plant growing in the hospital, and personally noted his inability to feel heat, cold and hunger. This infection was responsible for inhuman abilities he would exhibit, including the ability to withstand gunfire. When hunting for food for his "wife", Lester concealed his identity with a black hood and adopted the new persona of the "Axe Man".