A mother accused of suffocating her 3-year-old son and burying him in an Albuquerque playground was indicted Monday on murder and child abuse charges.

Tiffany Toribio, 23, is accused of killing her son, Ty, on May 13 as he slept on a climbing gym and then burying him in the sand.

Toribio was charged Monday with an open count of murder, child abuse resulting in death, tampering with evidence, failure to report a death and concealing her identity. Her lawyer said she would plead not guilty.

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Toribio is being held in a mental health unit at the jail, said Jeff Buckels, Toribio's defense attorney. Police said she attempted suicide hours after her arrest.

If convicted of the most serious charges against her, Toribio faces a maximum penalty of life in prison.

The boy's body was discovered when a mother playing in Albuquerque's Alvarado Park with her children saw the boy's shoe sticking out of the sand and called police after trying to pick it up and realizing it was strangely heavy.

Police worked for six days to identify the boy until an artist's rendition of him led to a tip that he was Toribio's son.

Hours after police publicized Toribio's photograph, they received a tip that she was on her way to the police station. When officers stopped her on the street, she at first denied who she was, police said.

In the days leading up to Ty's death, Toribio had been kicked out of her mother's home and a friend's apartment over concerns she was neglecting her son, police said.

Bernalillo County Attorney Kari Brandenburg said investigators must look at the credibility of conflicting accounts from those who knew Toribio before any decision can be made regarding charges for failing to report neglect.

"The child reportedly was very healthy, very well-nourished and looked well taken care of, so there has to be something really clear for them to report," Brandenburg said.