Two Manchester teenaged stepbrothers are being credited with helping to catch a robber. Victor Rosario and Jonathan Tavares witnessed a robbery at the CVS on Mammoth Road early Monday morning. The teens followed the suspect down to Exit 5 in Derry. All the while, staying on the phone with police. At some point the alleged robber showed a knife and told the teens to leave. That’s when police arrived and arrested Seth Skillin and Robbi O’Rourke. Skillins had $900 hidden in his pants.