Her older sister, Nancy Cardenas, described Maura as someone who loved to sing, dance and laugh.
"If you asked her a question, she could answer you in yes or no," said Cardenas. "She was just like all of us, just delayed."
Cardozo died in late July at Antelope Valley Hospital and was reportedly admitted with a 107-degree fever. Cardenas doesn't know why Cardozo died - she doesn't even know how. But she's not surprised it happened.
"When I called Child Protective Services, that's the first thing I said. My biggest fear is that something's going to happen to her because he neglects her," said Cardenas, referencing Cardozo's father, who the family says got custody of her shortly after their mother died.
Cardenas told ABC7 that over time, the Lancaster house where Maura lived became a mess, adding that her sister was dirty, trapped and voiceless.
Cardenas has decided to speak up, in the form of a claim notifying the Los Angeles County department that oversees Adult Protective Services of her intention to sue. Attorney Brian Claypool represents the family.
"As to why in the world the father has not been arrested for child neglect... We've seen people arrested for mistreating dogs," said Claypool. "This was a human being."
ABC7 reached out to the L.A. County Sheriff's Department and the district attorney.
An LASD spokesperson said: "Due to the active investigation, we are unable to comment directly about the incident. What we can tell you is an investigation team is conducting interviews and will be reviewing the decision making process and the events leading up to the incident."
The District Attorney's Office responded by saying: "We are aware of this case and are in contact with detectives. However, a case has not been presented to our office for criminal filing consideration."
Cardenas says she filed four reports as she became worried about her sister's health, and that they all went unanswered.
A spokesperson for the Department of Workforce Development, Aging and Community Services, which oversees Adult Protective Services, told ABC7: "State law protects the confidentiality of records of individuals who may have come to the attention of adult protective services, therefore we are unable to comment."
Cardenas says she was with her sister when she died, and that she hasn't been able to cry about it until now.
"I'm just so angry," said Cardenas. "I haven't even had a moment to mourn my sister."