Maria Matias was born on August 10, 1943, in Santa Catarina, Brazil. Of Italian and Native Brazilian descent, she married Zein al-Abdeen Hassan Isa in 1963. Together they moved multiple times—North Carolina, New Jersey, Puerto Rico, Brazil, and eventually settling in St. Louis, Missouri, around 1986. They raised seven children, including their youngest, Tina, born December 3, 1972. Maria, a Roman Catholic, lived in a strict household that upheld traditional values. She learned Portuguese and, later, English alongside her family’s linguistic mix. Over time, Maria supported her husband's expectations—especially regarding their daughter Tina's behavior and cultural conformity.

On November 6, 1989, FBI surveillance captured a chilling moment: Zein stabbing 16-year-old Tina while Maria physically restrained her. This honor killing occurred in their St. Louis apartment. FBI recordings under a FISA warrant provided unambiguous evidence of Maria’s involvement as the victim was held down during the attack. Tina died from multiple chest wounds.

Zein and Maria were arrested shortly after.During trial on October 25, 1991, the jury found Maria guilty of first-degree murder after a brief deliberation. On December 20, 1991, she was sentenced to death alongside Zein. The judge emphasized that cultural background is not a defense for murder. Maria's death sentence was later reduced to life without parole. She remained incarcerated until her death on April 30, 2014, in Vandalia, Missouri.