Just Acquaintances

In 2010 a high school acquaintance of mine named Nick had a brother who went missing. He has yet to be found. About a year later, Nick also went missing. The police acquired no evidence and gave up the search for him, just as they did with his brother. I believed they were both gone for good until I received a package in the mail from Nick himself. Where has he gone, and why would he send it to me? We were just acquaintances...