A 71-year-old described by prosecutors as a handyman pleaded guilty Friday to the murders of three women at the same apartment complex who had hired him for help, authorities said. Kevin Gavin admitted to killing the three women between 2015 and 2021, the Brooklyn District Attorney’s Office said in a statement, which described Gavin as a “serial killer inside his own apartment building.” Gavin pleaded guilty to one count of first-degree murder and three counts of second-degree murder in exchange for a sentence of 30 years to life in prison, the office said in a statement. “This defendant exploited elderly women who trusted him, gained access to their homes, and murdered them in a series of brutal attacks that shocked the conscience,” District Attorney Eric Gonzalez said in the statement. “These victims were vulnerable neighbors who deserved safety and dignity, and instead had their lives stolen by someone they believed was there to help.” The defendant’s lawyer had no comment.…