Miami police have arrested 54-year-old Gregory Higgs and charged with first-degree murder and using a weapon while engaged in a criminal offense after they say he stabbed Charles Brown, 54, (a high school teacher) to death.The Miami Herald reports: "Investigators said Higgs and Brown were college friends in the 1970s, and Brown had recently broken off their seven-year romantic relationship. According to detectives, Higgs in recent months searched for answers by sending derogatory e-mails to high school administrators and Brown's family. Brown's refusal to give their relationship another try angered Higgs, police said, to the point that he decided to attack Brown on Thursday afternoon at his apartment at 2075 NE 164th St. Residents of nearby apartments called police minutes before the attack, reporting that a suspicious man was seen waiting in the hallway outside Brown's place at the Inland Towers Apartments, said police spokesman Thomas A. Carney. They called police again when that man was seen stabbing Brown to death -- and some residents even tried to stop him, police said. Police who searched for the attacker were guided by 911 callers, who tracked his movements as he ran throughout the apartment building."Old-man Gregory, pictured, was caught a short time later; he was drenched in Charles' blood.