This as police explain what may have led to the rampage.
The shooting happened just before 7 a.m. Sunday morning.
Detectives believe Aide Mendez, known by friends and family as Yvette, shot her children, and her cousin before turning the gun on herself.
She also shot and stabbed her common law husband. He survived the attack.
33-year-old Eduardo Lopez is the children's father.
Action News checked with the hospital on Monday night, and he was listed in serious condition.
Investigators say Mendez shot him in the neck, and then stabbed him several times.
While an exact motive hasn't been released, police say she was high on meth during the rampage.
A small memorial continued to grow outside the apartment Monday, where police say Aide Mendez shot and killed her two children, along with her cousin, Paul Medina, before turning the gun on herself.
Rosa Gutierrez said, "They were very little and I have kids of my own, you know, so I dropped off a candle and two little bears for them."
Rosa Gutierrez says Mendez appeared to be a dedicated and loving mother to her 18-month-old daughter, Aliyah, and three-year-old son, Isaiah.
But, detectives allege, behind closed doors, it was a different story.
Sunday, they confiscated three guns, $8 thousand in cash, 10 grams of meth, and a video proving Mendez and her cousin were high shortly before the shooting.
Keith Foster said, "The video clearly depicts both Paul and aide smoking what appeared to be meth and we have not had a toxicology report back as of yet."
Investigators say, they had visited the apartment several times before for domestic issues.
George Arandules, who shares a wall with the couple, says they were fighting the night before, as well as the morning of the shooting.
George Arandules said, "My wife woke up to her screaming, loud, she couldn't make out what she was saying, she was just screaming."
But, the biggest piece of evidence police have is from a seven year old neighbor girl, who had spent the night.
She woke up and witnessed at least one of the murders, before running home.
Meanwhile, Mendez's common law husband, Eduardo Lopez, managed to survive by banging on his neighbor's door, pleading for help.
Jesus Gonzalez said, "He said, hold me, hold me. My wife killed my cousin and she want to kill my kids."
Action News has also learned the couple had another daughter who died a few years back, from medical issues.
Neighbors say Mendez never got over the loss.
As for her two other children, they were both awake in the bathtub when they were shot.
On Monday afternoon, a single candle sat on the porch of the apartment where four lives were lost just a day earlier.
Shocked neighbors said they could not imagine what was going on inside the mind of a mother they say was wonderful with her children.
The night before the shooting rampage, one neighbor spoke to the suspect.
"Just that night she was upstairs, me and her were talking but nothing seemed out of the ordinary. I didn't think anything like this would happen. I didn't think she was capable of something like that, she was too nice," neighbor Sophia Fierro said.
What troubled Mendez is no mystery to those who talked to the mother of two often. They say Yvette never got over the loss of a daughter she had who passed away from a health condition a few years ago.
Mariah Gonzalez says she still spoke of the child in present tense and even continued to celebrate her birthdays, but she never thought her inner struggles would amount to such a severe outcome.
"The only thing I can say is maybe she was depressed and maybe alcohol was involved and you put two and two together and they're not a good combination," neighbor Gonzalez said.
Friends told Action News Yvette was drinking hours prior to the murder-suicide. Many heard arguing coming from the apartment hours before they heard several shots.
Some neighbors were aware the family had a gun in their home, and also a security camera on their porch to guard against unwanted intruders.
Stay with Action News and ABC30.com for the latest on this developing story.