SAN MATEO (CBS SF) — A 24-year-old man has been charged with murder for the death of his girlfriend’s 18-month-old son last year after the woman came forward and accused him of months of abuse, San Mateo County prosecutors said Tuesday.

Marco Antonio Alvarado-Cisneros appeared in court Monday on charges of murder, four counts of domestic abuse, kidnapping, robbery, false imprisonment and battery, according to the district attorney’s office.

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The alleged murder happened last year when Alvarado-Cisneros, 24, and his 21-year-old girlfriend were living together in an apartment just outside of Redwood City.

The woman went to work at about 2 p.m. on Aug. 12, 2014, leaving her 18-month-old son Dante Nava in Alvarado-Cisneros’ care. At about 7 p.m., Alvarado-Cisneros called 911 to report the boy was unconscious and not breathing and may have had a seizure, prosecutors said.

Alvarado-Cisneros told paramedics that the child was awake but when he turned away for a moment, Dante may have fallen off the bed, according to prosecutors. He said the child later appeared to be having a seizure.

Dante was pronounced dead a short time later. An autopsy found he had numerous injuries, including a massive subdural hematoma, hemorrhages on his retinas, days-old bruises and human adult bite marks, prosecutors said.

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But despite the autopsy’s findings, Alvarado-Cisneros was not arrested or charged. The mother was not cooperative with the investigation and while investigators concluded some abuse had taken place, exactly who was responsible remained unclear, District Attorney Steve Wagstaffe said Tuesday.

Alvarado-Cisneros continued to live with his girlfriend for months afterward. The two had a child together but the relationship was tumultuous, with deputies responding to numerous domestic violence incidents, according to prosecutors.

The woman came forward this month and reported that over the previous nine months he had repeatedly abused her, kidnapped and robbed her.  The investigation connected him to Dante’s murder, prosecutors said.

Alvarado-Cisneros remains in custody without bail. He is scheduled to appear in court again next Monday.

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