Two brothers are charged with murdering their parents at their San Jose home this past weekend, according to the Santa Clara County District Attorney, who also on Friday announced 17-year-old Omar Golamrabbi would be tried as an adult.

The teen is also alleged to be one of the authors of chilling messages found near his parents' bodies, according to prosecutors. NBC Bay Area has not named the high school student until now, as he had been considered a minor.

Like his brother, 22-year-old Hasib Golamrabbi was charged with the double murder of Golam and Shamima Rabbi, 59 and 57 respectively. They were found shot to death on Sunday in their Lucas Court home; prosecutors said Friday Golam Rabbi was shot more than a dozen times.

The younger brother entered a not guilty plea and his older brother did not enter a plea at their arraignment, according to Omar Golamrabbi's alternative defender Jessica Delgado. The older brother wore a yellow jumpsuit reserved for those in the mental ward. He was represented by Andy Guitierrez. The younger brother was arraigned in the hallway, and shielded from public view. Their next court date is set for May 5.

Prosecutors have not given a motive for the deaths. But they did indicate for the first time in court documents that there were two authors of black magic marker rants on the family's walls - and that the writing matched the handwriting of Omar Golamrabbi, who attended school on Monday as if nothing happened. The court documents do not state exactly what was written, only that there were "multiple sets of writing" that had been found in the home.

Sources who witnessed the aftermath told NBC Bay Area they saw a message that read: "Sorry my first killing was clumsy."

Prosecutors did not reveal who might have written the other messages.

In addition, prosecutors allege that the younger brother told police Hasib Golamrabbi had killed both parents, and then closed the garage door before they left to attend an Oakland anime convention on Saturday "to make sure that blood was not seeping out from inside the garage where his father had been killed to outside the house."

Apparently, there was a lot of blood.

"Golam was shot more than a dozen times. Sharma was shot once in the head," Santa Clara County Deputy District Attorney Matt Braker said after the arraignment.

For his part, Hasib Golamrabbi apparently admitted to shooting his father, but not his mother, court documents indicate. He also told police a stranger once assaulted him at the home and told him to commit the killing, court documents show. Omar Golamrabbi did not corroborate that with police.

"There are some unanswered questions in the case," Braker said, adding investigators are also looking into the motive.

The documents contradict the little bit that Hasib Golamrabbi told The Chronicle, in a jailhouse interview. NBC Bay Area also requested an interview with him, but he denied the television request, according to the sheriff's office.

“The best thing if anyone wants to know what happened is to wait for the trial,” Hasib Golamrabbi told the newspaper on Thursday.

“I want everyone to know what happened,” he told the Chronicle, “but I can’t say anything without a lawyer.” Asked if his brother had anything to do with the brutal deaths, Hasib Golamrabbi told the paper: “No, and that’s all I can say. He’s innocent.”

While prosecutors and police have remained tight-lipped about why two brothers would have killed parents that many in the Bangladeshi community have described as "soft and gentle," sources have told NBC Bay Area that the Rabbi elders did not agree with Hasib Golamrabbi’s “sexual orientation.”

Another, longer message written in marker near the parents' bodies, allegedly ended, "I can’t be like you, telling a lie. I can’t love someone without telling them," sources told NBC Bay Area.

The court documents mention nothing about the older son's sexual orientation.

At the same time the sons were being arraigned Friday afternoon, the funeral for both Rabbi parents was held. After the traditional Muslim juma'ah prayer, the burial for the Bangladeshi-born parents took place at the Five Pillars Farm Cemetery in Livermore.