The immigrant family advocacy group FIEL organized a march in Guillen's name that took place downtown Saturday evening.
Guillen is a Houston-native who went missing from Fort Hood in April and is presumed to have been murdered by a fellow soldier.
SEE ALSO: Family of fallen Fort Hood soldier Gregory Morales wants him buried with military honors
"Me and other people felt very strongly about the situation," said Andrew Rodriguez.
Rodriguez teamed up with FIEL to march alongside the Guillen family.
"You know, I have little sisters, little nieces. Some of them do want to join the military. When I see Vanessa, I see them," he said.
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"I cannot in good faith celebrate the 4th of July in peace knowing the events that have happened," an organizer wrote on Facebook. "Vanessa fought for us now it's time to fight for her!"
The group marched from Discovery Green and made their way to City Hall.
SEE ALSO: Houston artists pay tribute to Vanessa Guillen