Miami-Dade police are holding a 79-year-old man on charges he stabbed his 71-year-old estranged wife to death. The attack happened this morning in a home at Southwest 152 Avenue and 8th Way. Police say the couple broke up about four-months ago. Witnesses say the suspect tried to kill himself before he was restrained. A maintenance crew was working at a house near the crime scene on Southwest 152nd Avenue when someone heard the attack.