Hicks, 46, was charged with murder on Wednesday after calmly turning himself in to local police in the town of Chapel Hill shortly after the shootings which took place at 5.11pm local time on Tuesday.
In a tearful press conference, Hicks's wife Karen said the shooting had nothing to do with race but was born out of a long-standing dispute over parking.
Muslim groups immediately raised concerns over a possible religious subtext to the killings of the three students which also sparked a social media campaign under the hashtag #MuslimLivesMatter.
School photographs of left, Yusor Abu-Salha and Razan Abu-Salha, right
The hashtag, #ChapelHillShootings, continued to trend on Twitter on Thursday.
During the vigil, Farris Barakat, the brother of the slain dentistry student, Barakat, told the crowd: "If, and it is quite possible, this was an act based off of evil and a scared ignorant man, do not let ignorance propagate in your life," reported NBC News.
His sister, Suzanne Barakat said the support from the crowd was "what we need" following a statement issued by the families urging police to investigate the killings as a hate crime.
Ripley Rand, US attorney for the Middle District of North Carolina, said the killings were "an isolated incident [and] not part of a targeted campaign against Muslims in North Carolina".
The Council on American Islamic Relations also called for an investigation into a possible religious motivation.
“Based on the brutal nature of this crime, the past anti-religion statements of the alleged perpetrator, the religious attire of two of the victims, and the rising anti-Muslim rhetoric in American society, we urge state and federal law enforcement authorities to quickly address speculation of a possible bias motive in this case,” said Nihad Awad, the group’s executive director.
However the father of the two women, Mohammad Abu-Salha, a psychiatrist from the nearby town of Clayton told the local News & Observer newspaper that his daughters had recently complained about being harassed by their neighbour.
“It was execution style, a bullet in every head," Dr Abu-Salha told the Raleigh, North Carolina-based newspaper.
"This was not a dispute over a parking space; this was a hate crime.
“This man had picked on my daughter and her husband a couple of times before, and he talked with them with his gun in his belt. And they were uncomfortable with him, but they did not know he would go this far.”
Mark Kleinschmidt, mayor of Chapel Hill, attended the vigil and said: "I stand here tonight like you, with a broken heart.
"I have questions. I have questions about why and how this could happen. And I know you do, too. And we are going to struggle, we are going to hear thoughts from others who will try to label this experience as one thing or another
"But what I really believe we can hold onto, and what I think will be the greatest legacy of the three lives we lost, would be to remember who we are."
And according to one tweet, a vigil was held by Columbia students on Wednesday night. According to social media posts, many more vigils are planned including one on Thursday evening at the University of Los Angeles.