Erik Menendez’s lengthy parole hearing in California on Thursday contained several insights into his time behind bars – some of which factored into the board’s decision to refuse his request for release.

Along with his brother Lyle, Erik has spent decades behind bars for the shotgun killings of his wealthy parents in 1989, which was also discussed at the hearing. The brothers claimed self-defence, and have long pushed for their freedom.

Lyle has a hearing of his own on Friday. Here is some of what we learned about the killings and Erik’s time in prison, based on Thursday’s hearing, which he attended virtually.

The parole commissioner, Robert Barton, said the main reason for his denial was not the killings themselves, but Menendez’s behaviour in prison.

Barton rejected any notion that Menendez had been a “model prisoner”, though he said he was “gaining insight”. There was discussion of Menendez’s involvement in fights, drug use and even a tax-fraud scam while linked to a gang.

Menendez earned Barton’s censure over his possession of prohibited materials – in particular his repeated illicit use of a mobile phone.

“What I got in terms of the phone and my connection with the outside world was far greater than the consequences of me getting caught with the phone,” Menendez explained. But he said he had later rethought this view.

Menendez, who was 18 at the time of the crime, was asked why he and brother shot dead their parents rather than simply leave home.

He and his brother have long claimed the killings were a matter of self-defence, as their father was sexually abusing them.

“When I look back at the person I was then and what I believed about the world and my parents, running away was inconceivable,” Menendez responded. “Running away meant death.”

Asked why they killed their mother as well as their father, Menendez said he “saw them as one person” after he learned that his mother was aware of the abuse.

Acknowledging the impact of his crimes on his relatives, Menendez told the hearing: “I just want my family to understand that I am so unimaginably sorry for what I have put them through.”

The number of relatives who want to see the brothers released is now known to be more than a dozen. The group gave statements to that effect.

One of them, the brothers’ aunt Teresita Menendez-Baralt, tearfully said she forgave the pair for killing her brother. Explaining that she had late-stage cancer, she spoke of her wish to welcome Erik into her home to “wrap my arms around” him before it was too late.

Barton acknowledged the support, but told Menendez: “Two things can be true. They can love and forgive you, and you can still be found unsuitable for parole.”