Juan Manuel Alvarez, the 25-year-old who is accused of causing a fatal Metrolink derailment last month, pleaded not guilty today to 11 counts of murder and one count of arson, according to Jane Robison, a spokeswoman for the Los Angeles County District Attorney’s Office.

The arson charge was added today.

“The arson charge is consistent with the evidence obtained early in the investigation, and since forensically corroborated,” said Deputy District Attorney Patrick Dixon, head deputy of the major crimes division, in a press release issued earlier today.

The arraignment hearing comes after Alvarez’s lawyer, Eric Chase, had asked to delay the hearing for medical reasons affecting his client. He also asked that Alvarez receive a mental evaluation.

Eleven people died on two Metrolink trains that collided Jan. 26. One train derailed after Alvarez parked his SUV on the tracks in a failed suicide attempt.

A preliminary hearing in the case against Alvarez is scheduled for March 16.