This is the wrong question to ask. It assumes that God causes everything to happen-even initiating sin and tragedy. God isn't responsible if a person commits murder, so He doesn't have a "reason" for this sin. God doesn't cause things out of His will to happen, although He is in control of all things. That means He has the ability to bring good out of the bad things that happen.
A better question is, "Can God use anything that happens for His purposes?" The answer to that is YES. Romans 8:28 says, "And we know that God causes all things to work together for good to those who love God, to those who are called according to His purpose." This verse doesn't say that He causes all things to happen, but that He can cause all things to work together for good. God is sovereign and can "adopt" our mistakes, failures, and calamities, and work them into His plan. If He couldn't do that, no one would have any hope because we all have sinned and failed.
Before you ask Him to take control of the events in your life, have you asked Him to take control of your life? The promise of Romans 8:28 is for those who are "called according to His purpose." If you will submit yourself to His purpose, you can rest assured that He will work all things together for good.