The defence wound up its case last week after trying for three months to convince jurors that the brothers were not guilty of first-degree murder, an offence which could send them to the gas chamber.
The young men shot dead their father, Jose, 45, the multi-millionaire head of a Los Angeles video distribution company, and their mother, Kitty, 47, a former beauty queen, while they were eating blueberries and ice cream in the family room in August, 1989.
Every twist in the trial, broadcast daily on cable television, has been watched by thousands of viewers, intrigued that a family could have every trapping of the American Dream - self-made success, a dollars 4m mansion - and yet self-destruct.
Until days before the trial the brothers denied carrying out the shootings, at first believed to be the work of the Mafia. They then admitted the shootings, after a legal ruling which allowed the court to hear details of a confession they made to a therapist.
When the case began, it was hard to find any Menendez sympathisers. With their Armani suits and sports cars, they seemed sociopathic yuppies, whom greed and parental indulgence had turned into monsters.
But, as the evidence unfolded, the brothers began to attract supporters. They claimed they shot their parents because they thought their parents were about to kill them. They described a tortured household dominated by their father, who sodomised them and forced them into oral sex while their mother did nothing to stop it. Both said he abused them as young boys: Erik claimed this continued until the end; Lyle said his father stopped when he was eight.
Three days before the killings, Lyle Menendez, a 25-year-old Princeton student, claims he challenged his father over abusing Erik, 22, warning him that he would expose him if he continued. Jose Menendez, who hoped to be the first Cuban-born US senator, responded: 'What I do with my son is my own business. Don't throw your life away.' When they were ordered to their rooms on 20 August, they were convinced their parents were about to murder them. So they got out their recently-purchased pump action shotguns.
The 'battered child' defence hinged on persuading the court that they could reasonably fear a threat to their own lives - even if it did not exist. For weeks, the brothers seemed to be gaining ground.
Defence witnesses yielded abundant evidence that Jose Menendez was an insufferably domineering father, whose motto was 'cheat, steal, lie - but win'. Health experts testified that 'the boys' killed out of genuine fear.
Then came the bombshell. Judge Stanley Weisberg ruled that the court would be allowed to hear a tape-recording of a session between the brothers and a Beverly Hills therapist, Jerome Oziel. They were heard explaining that they killed their mother because they wanted to 'put her out of her misery', caused by their father's repeated infidelity. There was no mention of sex abuse, no mention of fearing their imminent death.
As in every good soap, there is a sub-plot. The defence said Mr Oziel made the tape for extortion purposes. It was not he, but his ex-lover, Judalon Smyth, who reported the confessions to the police, promoting the brothers' arrest. Ms Smyth hoped the police would respond by bringing charges against the therapist, whom she accused of raping her. When these did not materialise, she switched sides and testified for the brothers, accusing Mr Oziel of brainwashing.
As two juries (one for each brother) prepare to begin their deliberations, they may draw another comparison with soap operas: they contain very few nice people.