ABC13 obtained Joshua Armstrong's medical records that were part of a pre-trial motion.
RELATED: A.J. Armstrong: Retrial pushed back 4 to 6 weeks
In the opening statements of A.J.'s first trial last year, defense attorneys tried to illustrate Joshua's involvement in the killings of Antonio and Dawn Armstrong, arguing the older brother has a history of disturbing behavior and access to his parents' home at the time.
They also said he showed up at the home within minutes of the murders.
SEE MORE: A.J. Armstrong's brother's girlfriend tells jury he was home with her during double murder
In the first trial, A.J.'s attorneys were unable to admit Joshua's medical records as part of their case. In the motion filing for the second trial, the records show handwritten documents that not only label Joshua as schizophrenic, suicidal and depressive.
Under a form section for "History of trauma or loss," Joshua's psychiatric doctor checks the box for "Yes" and adds "saw parents murdered 2016."
Further, a summary of Joshua's voluntary admission for paranoia states that he doesn't believe A.J. is guilty.
"Patient states that in July 2016, both of his parents were murdered in their home. His brother is in custody as a suspect, although he doesn't believe that he is guilty," the document states.
While this was expressed, the summary goes on to illustrate a deeper mental breakdown in wake of his parents' deaths.
"Patient states that at this point he has accused everyone in his family of killing his parents, and is constantly interpreting their statements as a coded message that's a threat to kill him," the summary reads.
The records do not appear to identify who may have killed their parents, though, attorneys insist it's just short of a confession by Joshua.
FULL DOCUMENT: Defense attorneys' motion filing and Joshua Armstrong's mental health records
A.J.'s attorneys told Eyewitness News on Thursday the presiding trial judge has seen the motion, and a hearing is slated for Monday.
Rick DeToto, A.J.'s lead attorney, offered a statement in light of the pre-trial filing:
"This evidence places an alleged suspect, who is not AJ, in the house at the time of the murders. This is completely inconsistent with the prosecutor's theory at trial and casts reasonable doubt on their case.
This evidence confirms what we have been saying the last 4 years - AJ did not commit this crime. Throughout the pendency of this case the Houston Police Department and the Harris County District Attorney's Office have suffered from confirmation bias by ignoring and refusing to investigate exculpatory evidence showing AJ is not guilty. Further, their bias along with the passage of time has led to the destruction of this potentially exculpatory evidence.
The defense remains steadfast in our belief in AJ's innocence and prays that the Houston Police Department and the Harris County DA's Office will finally take this exculpatory evidence seriously."
ABC13 also reached out to the prosecutors in the case. As of Thursday morning, they have not responded to questions regarding the motion.
SEE ALSO: Inside the interview with a teen accused of killing his parents
FAMILY SHATTERED: The murder trial of A.J. Armstrong