The man convicted in the fatal shooting of a Bronx mother in 2009 was sentenced to 25 years behind bars Wednesday. 

Joseph Diaz had been found guilty of first-degree manslaughter after police say he fired the gun that hit innocent bystander Aisha Santiago as she stood with her 9-year-old son in Mott Haven. 

Prosecutors read a heartbreaking letter during the sentencing from Santiago's son, Anthony Flores, who is now 14 years old. It said in part, "There's not a day I don't think how my life would've been if she was still here." 

According to investigators, Diaz was aiming for someone who his friend had an argument with when he shot off a half-dozen bullets in the middle of the afternoon. Santiago, who was just 25 years old, was hit in the heart. 

Diaz also spoke in court, giving an emotional apology to Flores for his loss before proclaiming his innocence. 

Flores ended his letter by saying that he wishes he still had his mom to help him learn right from wrong, and that he hopes to make her proud.