PHILADELPHIA (CBS) — The Philadelphia chapter of the NAACP held a news conference Thursday morning to express outrage over a judge’s recent decision to dismiss all criminal charges against Amtrak engineer Brandon Bostian.

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Bostian was at the controls when Amtrak Train 188 derailed on Frankford Curve in 2015. Eight people died and hundreds more were hurt in the incident.

A Philadelphia judge on Tuesday ruled state prosecutors did not present enough evidence against Bostian to sustain criminal negligence charges, and dropped the case.

NAACP leaders say the justice system unfairly allowed the white engineer to go free for an accident, while a black contractor was found criminally liable and convicted for the deadly salvation army collapse in 2013.

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Griffin Campbell, the contractor, is currently serving a 15 to 30 year sentence. The NAACP is working toward getting him a new trial.

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Excavator operator Sean Benschop pleaded guilty to involuntary manslaugter for his role in the collapse. Toxicology reports showed he had painkillers and marijuana in his system at the time.

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Benschop was sentenced to 7.5 to 15-years behind bars.