Poignant portrait of trans activist

In July 1992, transgender firebrand and Stonewall riots icon Marsha Johnson – a beaming, generous and inspiring fixture in New York’s Village scene — was found dead in the Hudson River. Ever since, the transgender community has refused to believe the police’s conclusion that her death was a suicide.

“How to Survive a Plague” filmmaker David France’s new documentary “The Death and Life of Marsha P. Johnson” examines the case through the recent investigative efforts of Marsha’s friend and longtime LGBT activist Victoria Cruz, an eyewitness for more than 50 years to the kind of violence, hatred and political neglect toward transgender women that have made them a tragically oppressed segment of society.

Between phone calls to authorities, interviews with Johnson’s confidants, and powwows with members of New York’s Lesbian and Gay Anti-Violence Project, Cruz pieces together clues — negligent cops, bigoted bashers, even mob connections — that might point to an answer.

Along the way, a sobering history of the gay rights movement is rendered through the lens of long-suffering transgender activists. There’s a touching portrait of Johnson’s equally firedup, gender-nonconforming compatriot Sylvia Rivera, who saw little respect for the glam-yet-rough likes of her and Johnson in the early days of an awakened movement that was mostly white and geared toward assimilation.

While Cruz wins us over with her emotionally charged amateur sleuthing, the weight of a constant struggle to not just gain acceptance, but survive fighting for it, gives France’s documentary a stirring poignancy.

“The Death and Life of Marsha P. Johnson.” Not rated. Running time: 1 hour, 45 minutes. Not rated. Playing: Laemmle Monica Film Center.