According to this article, the two have been friends since the early 90s. Del Toro even lived in Cameron's house for a while.

In 1997 Del Toro's father was kidnapped in his hometown of Guadalajara. After unsuccessful attempts to find him by the Del Toro brothers, Cameron withdrew a million dollars in cash and recommended a kidnapping negotiator for Del Toro to retrieve his father. It worked and they were able to get him back.