The defense at both trials argued there that was no plan by the Menendez brothers to kill their parents. The defense argued, in part, if this were a planned crime, why would the brothers use noisy shotguns in a residential neighborhood on a warm August night when windows would be open?
In a 2017 interview (https://www.today.com/news/lyle-menendez-t116758) Lyle Menendez said:
“Yeah, there was no plan. I mean, there was no alibi, no plan … it would be a crazy plan to use a shotgun in the middle of Beverly Hills. The houses are literally 10 yards apart and the police station is a quarter mile away.
“There’s no sane person who would have a plan like that.”
In his argument to the jury, Prosecutor David Conn noted a couple of “flaws” with the defense’s argument. First, Conn pointed out that “The defendants are not charged with a planned crime,” but “a premeditated crime.” Citing the testimony of Craig Cignarelli, Conn argued that that testimony showed “a premeditated crime, whether or not the details were worked out.”
Conn said another flaw with the defense argument was that, “just because you fire shots in the neighborhood, that doesn’t mean that people are going to recognize that it’s gunshots. That doesn’t mean that they’re going to know where the gunshots came from. That doesn’t mean that they’re going to call the police; and that doesn’t mean that you won’t have time to get away.”
Conn noted that the 911 dispatcher testified that she received no reports of any shots fired that night, no one called the police to report that shots were fired in the neighborhood. Conn found that “significant,” because, “it reflects the defendants’ knowledge, or conforms with the defendants’ belief that they could commit this crime; that they could shoot in that neighborhood and it wouldn’t even be reported; that they could get away without it being reported.”
Referring to the testimony of three neighborhood residents, Conn noted that two of them did not assume that it was gunshots, but assumed that it was firecrackers. The third witness, the 13-year-old (in 1989) son of one of the ‘firecrackers’ witnesses, heard what he thought sounded like gunshots, as opposed to fireworks, and wanted to call the police. The boy testified that “my mother persuaded me not to call,” because, “she said that I didn’t know everything, and that I shouldn’t just call the police. I’m not no expert in guns, therefore I shouldn’t alarm the police to something that probably wouldn’t ever be anything important.”
However, even had he called the police, the 13-year-old boy said that he wouldn’t have been able to tell police precisely where the gunshots were coming from, only that they could have come from any of eight houses to either east and north.
The boy did think to himself, “Who hears gunshots where I live?” Conn argued that that “seemed to explain what would be the reaction of someone in that neighborhood.” Conn went on to say, “That’s exactly the assumption that the defendants were operating under that night, no doubt. They knew. They lived in a Beverly Hills neighborhood. When are shots fired in a Beverly Hills neighborhood?”
Concluding, Conn said the brothers “correctly assumed that people in that neighborhood who heard the sound of gunshots would assume that it was the sound of firecrackers; and even if someone did assume that it was gunshots rather than firecrackers, how would they be able to determine where the sounds came from?”
Conn ended by saying that the brothers’ “actions and the aftermath of their actions proves only one thing, that they know their neighborhood better than we know their neighborhood.”
Personally I believe that the Menendez brothers had the plan to ambush their parents in a manner that was consistent with how they believed organized crime would commit the murders. What and when they discussed among themselves only the two of them know. But regardless of whether or not they worked out the details of how they were going to carry out the murders, there is overwhelming evidence that they committed premeditated first-degree murder.