The elderly couple accused of killing their son-in-law, New York Times executive Jonathan McKinsey, pleaded not guilty to first-degree murder with a special circumstance of lying in wait, a defense attorney said Monday.

Defense attorney Curtis Briggs argued that his client, Shili Chen, who is married to Shouyong Zhang, did not premeditate the shooting, NBC Bay Area reported. Instead, Briggs told NBC Bay Area that the couple, both 77, acted out of concern after seeing something disturbing while their son-in-law had a supervised visit with his children.

“My client was absolutely concerned for her own life and also concerned for her grandchildren,” Briggs told NBC Bay Area.

Alameda County prosecutors say Chen and Zhang watched and waited in a parking lot in Dublin, California, to attack McKinsey, who was embroiled in a bitter divorce and custody battle with their daughter.

Briggs said that McKinsey, 40, had previously threatened Chen’s life three times through a hit man. The couple purchased firearms in March to defend themselves, Briggs said, and were moved to act last month in the parking lot of a popular park.

“They are not cold-blooded killers. They didn’t premeditate anything,” Briggs told NBC Bay Area.

Briggs did not elaborate on what the elderly couple witnessed that drove them to kill their son-in-law.

If convicted, they could both face life in prison without the possibility of parole.

According to local police, 911 calls started coming in around 3 p.m. on Sept. 26 from terrified witnesses, many of whom were with their young children.

Several witnesses told police they saw a black Honda speeding out of the parking lot and later identified Chen and Zhang as the shooters, police said in a statement. Officers chased down the car and arrested the couple, according to the police report.

Nearly a decade’s worth of court documents revealed a deeply troubled marriage between McKinsey and his wife, Candice Jang, who has not been charged in connection with his death.

McKinsey’s death followed years of violent struggle between Jang and McKinsey, who started dating in 2008 and were married in 2011, according to Jang’s petition for a domestic abuse restraining order. They had three children.

McKinsey had recently filed for divorce and was scheduled to appear in court the same week he died, according to court records.

In separate petitions for restraining orders, McKinsey and Jang each argued that the other was physically and mentally abusive during their marriage. McKinsey and Jang both said they wanted full custody of their children, but McKinsey had an ongoing child abuse case that granted him only supervised visits.

The children were living with Jang and her parents when McKinsey was shot.

He had been previously charged with two misdemeanors — cruelty to a child by endangering health and corporal injury to a child. McKinsey was freed on $50,000 bail and had been trying to enter a mental health diversion program, according to court records. Had he successfully completed the program, the charges would have been dismissed.

According to police reports, Zhang admitted to shooting McKinsey with his firearm during interviews with investigators. The husband and wife were each carrying weapons at the time of their arrests.

“Chen and the passenger carried out this shooting in a crowded park parking lot with blatant disregard for public safety where several children were present,” the arresting officer said.

McKinsey allegedly threatened to kill Chen at least three times, NBC Bay Area reported. A bail hearing was set for Nov. 4, followed by a pretrial hearing on Nov. 23.