Buy Photo

Casey Christie / The Californian

Alexis Dixon during her arraignment in Kern County Superior Court.

A Bakersfield mother accused of killing her 4-year-old son tearfully pleaded not guilty to charges of murder and assault on a child younger than 8 resulting in death Wednesday afternoon.

Alexis Dixon, 31, wore paper clothing in court, a sign that she is on suicide watch. Her bail was kept at $2 million and a preliminary hearing scheduled for April 16.

She said she could not afford an attorney, and Judge H.A. "Skip" Staley assigned the Kern County Bar Association's Indigent Defense Program to her case.

Dixon is accused of killing Mark Allen Dixon. The child suffered injuries April 23, 2010, and died a day later at Children's Hospital Central California in Madera.

Deputies have long said Mark's death was suspicious, but tissue studies and more investigation were needed before Dixon's arrest late Monday evening.

Her husband, also named Mark Dixon, defended his wife outside the courtroom following her arraignment. He said he doesn't understand why his wife has been charged.

"They're making a tragic mistake, a tragic accident, into something it's not," Dixon said of prosecutors.

Alexis Dixon has declined an interview request from jail.

Deputies have said Mark was suffering from suspicious injuries, including head trauma, when they arrived at the family's travel trailer in the 22000 block of Stockdale Highway. The boy's injuries were not consistent with explanations given as to how he had been injured, authorities have said.

Deputies said there were "dozens and dozens" of scars on his body.

Alexis Dixon told investigators she'd been lying down in another room in the trailer when Mark hit his head after falling from a 2-foot-tall table, according to a search warrant. She said she placed the boy by a wall outside the trailer, but he slid down and hit his head on a pole, causing further injury.

Dixon was the only person around when Mark suffered his injuries, deputies said.