Just before 4 p.m. on May 5, Bampumim Teixeira snuck into the garage of the Macallen building in South Boston, carrying a backpack with duct tape, a tactical knife, two fake guns, and a mask, prosecutors say.

At some point in the next hour, he made his way to the 11th floor penthouse where Dr. Lina Bolaños had just returned home. When Bolaños’ fiancé, Dr. Richard Field, arrived home 90 minutes later, he texted a friend that there was a gunman in the house and it was serious.

When police arrived, they shot Teixeira inside the penthouse and found a gruesome scene: both doctors had been bound and stabbed, and a backpack had been stuffed with Bolaños’ jewelry.