(KRON) -- Evidence uncovered in a murder investigation, which involves two elderly grandparents accused of gunning down their son-in-law at a Dublin sports park, was revealed in new court documents filed by a defense attorney. Attorney Curtis Briggs, who is representing 77-year-old grandmother Shi li Chen, filed a lengthy motion Thursday asking a judge to grant bail when she returns to court on November 4. Briggs' motion details discoveries and evidence that, according to Briggs, show Chen's husband plotted to kill Jonathan McKinsey without Chen's knowledge. "Santa Rita jail is no place for an ailing grandmother with no criminal history," the defense attorney wrote in court documents. "For Ms. Chen, detention before trial may become a death sentence without a conviction." Jonathan McKinsey is seen in his LinkedIn profile photo. (Photo via LinkedIn) On September 26, the victim went to the park for a court-ordered visit with his children. McKinsey, 40, of Dublin, was a father-of-three who worked as a software engineer for the New York Times’ gaming platforms. He was also embroiled in a bitter divorce and intense child custody battle with his estranged wife, 46-year-old Candice Jang. Police said the septuagenarians both opened fire on their son-in-law using two guns, and the violence was recorded on surveillance cameras. Prosecutors charged Chen and her husband, 77-year-old Shouyong Zhang, with premeditated first-degree murder. Briggs wrote, "Mr. Zhang had purchased both firearms early in the year because he was afraid. Mr. McKinsey had threatened to kill Ms. Chen, had previously assaulted and broken Mr. Zhang’s rib, and had brutally beaten their grandchildren. Mr. McKinsey had an explosive temper so Ms. Chen began keeping a firearm for protection." On the day of the homicide, Chen "was in the dark" about what Zhang was planning to do to their son-in-law when they arrived at the park, the defense attorney claimed. Chen was allegedly still sitting in a car when Zhang fired the first shots, and he continued shooting while the victim lay motionless on the ground. Shouyong Zhang and Shili Chen are seen in mugshots released by the Alameda County Sheriff's Office. An off-duty Milpitas police officer was at the Dublin Sports Grounds park when he saw an Asian man and woman standing over McKinsey, and saw the woman fire seven rounds into him, court documents state. Briggs claims his client only shot McKinsey because she heard gunshots and feared Zhang was in danger. The defense attorney wrote, "The prosecution may attempt to argue that Ms. Chen is the actual killer but that would be a strain on the facts here since Mr. Zhang fired so many shots into Mr. McKinsey’s chest and head before Ms. Chen arrived." When Zhang was questioned by sheriff's deputies, he said his son-in-law was "violent and aggressive all the time with the kids," court documents state. The grandfather had grave concerns for his grandchildren's safety, and Zhang "made continuous statements that Mr. McKinsey was evil and had an evil soul," Briggs wrote. Dublin police said Zhang confessed to the shooting. Detectives later searched Zhang and Chen’s one-bedroom apartment on Lockhart Street and found four photo albums. "Several photographs of Mr. McKinsey in the albums had portions of his face cut out. One had black marks and dots drawn on his chest and over his right eye in places that appeared consistent with where he was later shot. Detective Tambar concluded that the photographs suggested Zhang had focused on McKinsey prior to the homicide and that Zhang had formed an intent to target McKinsey," the defense attorney wrote. Briggs said Zhang lived in the apartment, while Chen primarily lived at her daughter's house to help take care of the three children. After her husband was killed, Jang called Chen in jail at least five times. In the recorded calls, they spoke about childcare, checked on each other’s well-being, and told each other "I love you" multiple times, according to Briggs. Jang has not been charged with any crimes. Her parents pleaded not guilty to all charges. Just one week before McKinsey’s death, he was slated to appear at a child custody court hearing to ask an Alameda County judge for more child visitation rights. McKinsey had filed for divorce in December of 2025 and was seeking to re-gain custody of his children, who are between ages 2-6. McKinsey, who was a transgender man, accused his in-laws of transphobia, court records show. Jang and McKinsey accused each other of child abuse and domestic violence. In the bail motion, the defense attorney is requesting for Chen to be released from Santa Rita Jail so she can live with her daughter in Dublin under home detention and GPS electronic monitoring conditions. Alameda County Assistant Public Defender Jennie Otis told KRON4 that Zhang is physically frail, shows signs of dementia, has never been in trouble with the law before, and should also be released from jail pending trial. ...read more read less