A man who led a public crime fight in Kansas City after his teenage son’s 2009 killing is headed to prison.

42-year-old Nelson Hopkins Sr. was sentenced to 20 years in prison Friday for an armed robbery committed last summer in suburban Blue Springs.

Hopkins had organized Operation Promise Land, a nonprofit aimed at fighting violent crime by encouraging witnesses to cooperate with police. Hopkins also became a paralegal and started a business to help inmates prepare parole plans.

Friends had urged Jackson County Circuit Court Judge Jack Grate to impose a lighter sentence, stressing that the Marine veteran suffered from post-traumatic stress disorder.

But prosecutors pointed out that Hopkins had served about 10 years in Missouri and Kansas prison for other