I believe the only living witness to this event is Ronnie, himself. Apparently there was a violent argument one day between Dawn DeFeo and her father. For whatever reason, Ronnie was fed-up and decided to end the argument by pulling a gun on his father. It was loaded, Ronnie pulled the trigger, but the gun misfired and Ronald Sr.'s life was spared.

It is generally believed that this event took place, yet I don't believe anyone else but Ronnie has ever mentioned it.

During the trial, William Weber tried to convince the jury that Ronnie was legally insane during his murder spree. Ronnie's story has changed quite a bit over the years. Currently, he claims he only shot his parents, and that Dawn killed the children (prompting Ronnie to kill her in turn).

Some say Ronnie was high on drugs — possibly acid — during the murders and didn't know what he was doing.

The police have felt that Ronnie murdered his family in order to claim a life insurance policy.
Still others believe Ronnie was possessed by an evil force present in the house.

According to one version of the events that night, Ronnie stated he was watching the film "Castle Keep" on television, and during the movie he heard his family whispering. He felt they were plotting to kill him. Around the end of the film, Ronnie said he was handed a rifle by a person with black hands. He then went and killed his family members, starting with his parents. William Weber has stated that after killing his parents, Ronnie shot his two younger brothers, his youngest sister, and then went upstairs to kill Dawn, his older sister.

Concerning the murders that night, Ronnie has stated, "I couldn't stop if I wanted to" and "I felt somebody was inside moving me."

I'm not sure it's definite that the family members were, in fact, asleep during the murders. If Ronnie moved quickly enough, his siblings could have been asleep or just waking up when they died; but it is possible Ronnie could have taken his time and simply ordered his siblings back into their beds. With Ronnie on the 2nd floor landing (with a gun) he could easily have blocked his sibling's escape.

It was rumored the family was drugged at dinner that night, which prevented them from awakening during the shooting. Later tests of the victims' bodies, however, showed no traces of any such drugs.

This is apparently true, although now it seems some neighbors may have actually heard the shots that night, but simply ignored them, either thinking it was Ronnie playing with his guns again, or perhaps being fearful of the family's alleged mob connections and not wanting to get involved.

Some people, such as Hans Holzer, think the gunshot sounds were muffled by a strong psychic energy in the house.

Apparently the DeFeo's dog heard something, as it was reported to have been barking around 3am that morning.

Unknown. In a 1979 interview, Ronnie DeFeo mentioned his family heard noises at night, such as banging pipes, footsteps and the sounds of people screaming. Unfortunately, it is difficult to know if Ronnie believed this at the time and/or still believes this today. Ronnie has said many things in the past which he denies today, so we can't say for sure.

It is reported that after the incident with the misfiring gun (see above) Ronald Sr. felt very spiritual and lucky to be alive. He surrounded the house with religious statues. Some say these were specially-blessed statues coming from St. Joseph's Oratory of Mount Royal, Canada. When asked why he surrounded the house with the religious icons, Ronald Sr. reportedly answered that he had "a devil on his back."

It is unknown if that comment was referring to his son or possible evil spirits in the house.

There are also unconfirmed reports that the DeFeos had a special mass held in their home. According to Ed Warren, Mr. DeFeo brought in a priest from St. Joseph's Oratory to perform this mass, which was hoped to rid the house of any evil or demonic forces. According to Mr. Warren, during the mass there was much supernatural phenomena occurring, such as candles mysteriously toppling over and doors opening/closing on their own.

St. Joseph's Oratory has officially denied knowledge that any of their priests may have been involved in this incident.