As a result of handling these snakes, Haast had been bitten 172 times by mid-2008,[4] all of which but the last few were validated by the Guinness Book of World Records "for surviving the most deadly snake bites", a distinction Haast disliked as he did not think being bitten was a goal to be attained or admired.
Haast started collecting snakes and, after initial opposition from his mother, was allowed to keep them at home.
Haast eventually returned home, where his mother had leased a concession stand at a lakeside resort.
After his wife became pregnant, Haast lost his job when the speakeasy he was working at was raided by IRS agents.
The couple moved back to New Jersey, where Haast studied aviation mechanics, and was certified after four years.
He bought a plot of land facing U.S. 1, south of Miami, then sold his house and started construction on the Serpentarium.
Haast retained custody of their son, Bill Jr. and continued to work as a mechanic for Pan Am while he built the Serpentarium.
Soon after opening the Serpentarium, Haast began experimenting with building up an acquired immunity to the venom of King, Indian and Cape cobras by injecting himself with gradually increasing quantities of venom he had extracted from his snakes, a practice called mithridatism.
[7] In 1949, he began supplying venom to a medical researcher at the University of Miami for experiments in the treatment of polio.
The experiments gave encouraging results, but were still in preliminary clinical trials when the Salk polio vaccine was released in 1955.
Haast shot the crocodile, which weighed 1,800 pounds (820 kg), nine times with a Luger pistol, yet it was still an hour before it died.
Haast's mental trauma over the boy's death eventually led to the closure of the Serpentarium on South Dixie Highway.
In 1990 he moved to Punta Gorda, Florida, with his snakes, where he established the Miami Serpentarium Laboratories.
Haast's hands suffered venom-caused tissue damage, culminating in the loss of a finger following a bite from a Malayan pit viper in 2003.