article_snippet: Prosecutors called Silva, 21, to the witness stand to . discuss the loan of the rusty Ruger P95 handgun they contend was . used to shoot dead Massachusetts Institute of Technology police .
article_snippet: Stephan Silva has pleaded guilty to federal gun and drug charges, .
article_snippet: Stephan Silva . testified Stephan Silva had gotten gun and drug from a friend, intending to use .
article_snippet: gun and drug to protect Stephan Silva drug business, and also used gun and drug in a robbery.
article_snippet: committing a robbery, Stephan Silva testified.
article_snippet: On loan: gun and drug was part of evidence shown in court on Tuesday.
article_snippet: used 'peer pressure' to persuade Dzhokhar to smoke marijuana, . which Stephan Silva sold. '