Around 9:30 p.m., two assassins on a motorcycle shot Manrique Valencia twice, killing him in front of his house in the Cafe Madrid neighborhood.
He was an operator of the multinational cement company Cemex Colombia.
"He was a Cemex worker for 10 years, a very active member of the construction union. He was disabled because he had suffered a traffic accident six months ago. We totally denounce his murder, we have the right to life," said Miguel Sierra, another union leader of SUTIMAC.
The reason for his assassination is unclear but it raised alarm among other union leaders who fear for their safety now.
"The Presidency of the Republic is already aware of the case, the Workers' Union has already informed the National Government so that the Prosecutor's Office can give us results about the crime," Sierra added.
Since the foundation of SUTIMAC in 1972, more than 40 leaders of the union have been killed, and none of the crimes were solved.
The investigative authorities are on the case now and trailing the two assassins who fled the crime scene.