Deshawn Morgan was immersed in Chicago’s West Side gang culture before he was even out of grade school, dealing drugs at age 12 and rising in the ranks of the Mafia Insane Vice Lords. Along the way, Morgan told a federal jury last week, he befriended key players in the complex hierarchy of gang factions in the city’s Austin and West Lawndale neighborhoods. His testimony provided a rare glimpse at the kind of gang conflicts that often drive Chicago violence. He earned respect by hewing to a strict street code against snitches. He got shot and shot others, was charged with murder in his 20s only…