If convicted, both Yarelly and Martin Arroyo-Morales could face life without the possibility of parole or the death penalty.
FRESNO, Calif. (KFSN) -- New details are emerging about the murder of a young Fresno mother and her weeks-old baby.
Yarelly Solorio-Rivera, the sister of the victim, and her boyfriend, Martin Arroyo-Morales, were charged with the murders and made their first court appearance Tuesday morning.
Court documents show it was Yarelly Solorio-Rivera who called 911 the morning her 18-year-old sister Yanelly Solorio-Rivera and her 3-week old baby Celine were shot and killed in their Southwest Fresno home.
It was also Yarelly who pointed the finger at other possible suspects in the case.
But Tuesday, it was she who was in handcuffs alongside her boyfriend, and father of her two young children, Martin Arroyo-Morales charged with their murders.
Close family friends of the victims showed up to the hearing to show their support for the victims.
"When we found out the news, like that she's the one who did this to her own sister, we were very shocked," said Aurelia Villa-Medina.
Newly obtained court documents show investigators were suspicious of Yarelly early on.
They say she lied about who she was with the night before the shooting, claiming she was with a friend, when cell phone evidence ultimately showed she was with Arroyo-Morales.
Arroyo-Morales is a verified gang member. He was also charged in December with having unlawful sex with a minor.
During a follow-up interview, a family member admitted to police they saw Arroyo-Morales run from the garage with a gun after Yanelly and Celine were shot.
And police say surveillance video collected from a nearby business put him near the scene the morning of the murders.
Chief Paco Balderrama said at a press conference last week that the video was crucial to the case.
"And that is when the lies, deception and the evil intentions surrounding this case began to unravel." Chief Balderrama said.
Yarelly and Arroyo-Morales were detained by police and, at first, Yarelly told detectives she was part of the planning but didn't shoot.
After telling officers where the gun was hidden, she eventually admitted she was the one who pulled the trigger.
Yarelly told investigators she could no longer live with Yanelly.
Court documents said, "She was sick of Yanelly and the baby getting all of her parent's attention and her kids were getting none."
Arroyo-Morales admitted to officers he was there, there was a plan and Yarelly gave him the gun after the shooting.
Those close family friends say jealousy does not justify what happened to Yanelly and Celine.
"I just want justice for her, for that little innocent baby that she just had, that's not right what she did," said Villa-Medina.
Both suspects are being held without bail.
If convicted, they could face life without the possibility of parole or the death penalty.
They are expected to be back in court on December 8.