Congratulations, you have completed the investigation.
It turns out that your friend was dating Lucia and he found out that Lucia was cheating on him with an older guy, Tom. When he finds out, he confronts Lucia which doesn't end well. She takes a hot frying pan staight off the stove and smacks him in the head with it. He falls to the floor unconscious so she gets scared and calls Tom to help her clean up the mess.
You should try getting into investigating. Great work.