He's accused of strangling his ex-wife, Deanna Cook, whose body wasn't discovered for two days because of a 911 mistake.
Her death prompted an overhaul of Dallas 911 operations, but her family is now focused on a conviction.
The trial has been delayed three times, prolonging closure for the Cook family.
Patrick is dead to them, but they want to make sure he is prosecuted to the fullest extent of the law.
Their message goes beyond a verdict –- Cook's sisters hope that her story can rescue other women from domestic violence.
On Aug. 17, 2012, Cook called 911, screaming and pleading for her life for 11 minutes. Police say she was under attack by Patrick.
But officers didn't come to her rescue. It took them 50 minutes to respond because of stops along the way, including a false burglary call and personal purchases at a 7-Eleven, and when they did finally arrive at Cook's home, no one answered, so they left.
Two days later, Cook's mother called 911 requesting a welfare check, but the operator told her to call jails and hospitals instead.
After kicking in her front door, family members found Cook lying dead in her bathtub.
That 911 operator was later fired and two others were reprimanded. Additionally, the City of Dallas overhauled its 911 operations and hired more call takers after Cook's death.
It also helped spawn Mayor Mike Rawlings' campaign to end domestic abuse.
"What we experienced was horrible and what we have to live with, the memories, is horrible, but at the same time, I'm glad a light was shined on this situation so the changes could be made in the system," said Cook's sister, Karletha Gundy.
Cook's other sister, Valecia Battle, chose not to listen to Cook's 911 call, but she wants the jury to hear every single word.
"I think it's a necessity to understand what was going on and exactly what the dispatch heard and exactly what was happening at that moment and what allowed police officers to stop," said Battle.
FOX 4 contacted Patrick's attorney for comment on the trial and claims of his client's innocence, but our calls were not returned.
Patrick has an extensive criminal history, with previous arrests for assault, drug possession, resisting arrest and aggravated robbery.
He faces life in prison.