Hundreds of people took to the streets on Friday evening to protest against the killing of George al-Reef two days earlier by an enraged man following a feud over a car collision.
About 200 people marched in Beirut’s Gemmayzeh Street, a commercial area packed with restaurants and pubs, where Wednesday’s incident - filmed by a number of bystanders - took place.
A video footage published on social media showed the perpetrator, Tarek Yatim, stabbing Reef up to 15 times while his wife screamed helplessly near them.
Yatim was detained by military intelligence on Thursday, the army said in a statement.
A jounalist in the Beirut told Bloom Gist that the perpetrator was connected to an influential businessman who had in the past managed to get him out of prison several times.
"The incident exposes the culture of impunity in the country," she said. "In this atmosphere, crimes like that are bound to happen.
"Had Yatim been punished and serving a sentence in jail, this crime wouldn’t have happened and George would not have died," she said.
Yatim was associated with a nightclub shooting in Beirut in 2010 and an attack against a school teacher.