Surveillance video from last Thursday morning allegedly shows a burglar trying to break into a home on Berkeley Way in Tulare, California.
It appears he sees the camera then turns and moves on another home nearby.
That's where police said Fabian Gamez, 30, tried to enter through the backyard, when he was confronted by the owner, Melissa Quinn, 58.
Gamez attacked Quinn with a knife, then her son Raymond Garza,38, tried to intervene and Gamez began stabbing him, detectives said.
The mother and her eldest son both died from their injuries.
"Losing them, not just one but both at the same time, is a huge hit to the family. They were our protectors and if anything happened they were the first to defend their family members," said Michael Garza, who is Melissa's second son and Raymond's younger brother.
He says their youngest sibling heard the commotion, came out and shot the intruder.
He was able to keep the suspect from getting away until police arrived.
There were more than six people in the home, including Melissa's father she cared for and Raymond's children, ages 7, 9 and 19.
The two youngest kids also lost their mother in 2019 and are now coping with the trauma of another tragedy.
"They are scared, what my nephew had to see his dad dying on the floor after being viciously stabbed by the intruder," said Michael.
ABC Fresno affiliate KFSN found Gamez has a history of run-ins with police.
Detectives believe he'd been canvassing the area Wednesday night.
"Detectives now believe that he may have been burglarizing in the area," explains Sgt. Rosa Moreno, with the Tulare Police Department.
Gamez pleaded not guilty Tuesday to two counts of first degree murder and one count of residential burglary with special circumstances.
The victims' loved ones say they will continue to fight for justice as they honor the mother and son.
"They were the limelight of any event they'd show up. Their personalities were always glowing," said Michael.
The family now left with only memories and heartbreak.
Melissa leaves behind six grandkids and two sons.
Raymond leaves behind his three young children. He was their only living parent.
The family has set up a GoFundMe page to help with funeral expenses.
Gamez will be back in court next month.