A jury has convicted a Gardner man of second-degree murder for the March 4 shooting of a family member at a birthday party in Baldwin.Jurors brought back their verdict about 4:45 p.m. after nearly three days of trial for Hinndley K. Espinales, 25. Prosecutors had charged Espinales with premeditated first-degree murder in the death of Alvin Sanchez, which would have carried a penalty of 25 years to life. The lesser charge of second-degree murder carries a minimum penalty of nearly 13 years.He will be sentenced Dec. 5.