jurors begun deliberations in aaron hernandez 's murder trial on tuesday afternoon after the prosecution and defense made their closing arguments .
the former new england patriots football player is accused of killing semi-pro player odin lloyd , who was dating his fiancee 's sister , in june 2013 .
his defense said on tuesday that he witnessed his friends , ernest wallace and carlos ortiz , kill lloyd but did not commit the shooting himself .
his lawyers said the prosecution has not proven he pulled the trigger .
hernandez faces life in prison if convicted of the murder .