Meet Dawn DeFeo:

 

Born on July 29, 1956, Dawn DeFeo was born. She was the second oldest out of Robert and Louise DeFeo's children, Robert Jr. being the oldest.

During a November 30, 2000 meeting with Ric Osuna, author of The Night the DeFeos Died, Butch DeFeo confessed that, along with his sister Dawn DeFeo, he and one of his friends actually committed the murders out of desperation. This fact was confirmed by a letter written by Butch DeFeo. In his own handwriting, Butch wrote, "...it was cold-blooded murder. Period. No ghosts. No demons. Just three people in which I was one."

During the 2000 interview, the details of the hours leading up to the six killings emerged. The DeFeo household had been in a frenzied state during the evening of November 12, 1974. Butch's father, according to Butch, routinely abused his family. After that evening's tirade had settled down, Butch, his 18-year-old sister Dawn, and two of Butch's friends proceeded to get "high" in the basement.

Incensed that her father was preventing her from joining her boyfriend in Florida and worn out from the years of physical abuse, Dawn DeFeo approached her older brother about killing their parents. Butch initially refused. After a culmination of drugs, alcohol, and desperation over the next few hours, Butch finally gave into Dawn's ghoulish request. Employing his two friends, Butch and Dawn left the safety of the family's basement and headed for their parents' bedroom on the second floor. It was around 1:00 a.m. on November 13, 1974. While one friend waited as a lookout, the other, with his Colt Python, followed Butch, who had armed himself with a .35-Marlin rifle.

Butch claimed that his sister was the one who shot her two younger siblings although the claim was never proven true. The only evidence to support this theory is the post mortem examination that discovered Dawn had "unburned" powder burns on her nightgown, which lent further credence to Butch's claims of his sister's involvement.

-http://www.amityvillemurders.com/murders.html