As for all developing countries, every company needs to assess whether or not it's a good idea. You're right that Colombia is still a violent place. It can be a dangerous place, and that's part of the assessment that companies make.
Canada is a world leader in the extractive sector, and those are generally the companies that go into these types of markets early. The Canadian mining industry is the largest foreign industry in that sector in Colombia.
So yes, there are companies that are going there, and there are more that are looking at it. They are generally sophisticated companies that understand the dangers and how to mitigate them. It's not a market for everybody, although it's important to understand that much of the unfortunate violence that takes place in Colombia is very targeted to specific sectors.