Johnny Wactor's Friend Organizes March in Downtown L.A. Month After Murder

Johnny Wactor's close friend is pressuring L.A. officials to find his murderers and hold them accountable ... organizing a march through downtown to keep the late actor's memory alive.

Micah Parker -- a fellow actor and one of Johnny's best pals -- spearheaded Wednesday's march, and we talked to him in the street  ... with him telling us Johnny's murder should be a wake-up call for the city, hoping those in power acknowledge there is a problem with crime.

TMZ broke the story ... Johnny was shot and killed by a group of thieves who were trying to steal his catalytic converter ... a type of theft that many Angelinos are very familiar with.

There was a solid turnout for Wednesday's rally, which Micah says is emblematic of people being tired of going unheard.

Outside city hall, demonstrators carried signs calling for #JusticeForJohnny ... and they picketed with cardboard cutouts of Johnny's face, leaving flowers and candles at a makeshift memorial. We even talked to Johnny's ex-fiancée, Tessa Farrell, who was in the crowd too.

Remember ... Tessa spoke out against Johnny's murder in the aftermath, and caught some heat from his family. But here, she's incredibly sincere ... not to mention, emotional.

As we first told you ... Johnny's body was cremated and his remains are being sent back to South Carolina, where his family lives.

There've been no arrests in the case so far ... but cops are working on some leads.