Authorities are investigating whether a new designer drug played a role in a gruesome Los Angeles homicide that involved a young actor.

Johnny Lewis, who appeared in the series “Sons of Anarchy,” is suspected of being under the influence of 2C -I (also known as “Smiles”) when he allegedly beat his 81-year-old landlady to death and then attacked a neighbor. The neighbor managed to escape and Lewis was later found dead by police after he apparently fell from a wall at the neighbor’s house.…