A Calgary man has died of his injuries almost four months after he was viciously beaten in the city's Beltline neighbourhood.

John Herrera was attacked in May.

The 49-year-old was carrying groceries when police believe three people beat him up.

Police say the beating was unprovoked.

Three people are now facing attempted murder charges.

The Crown prosecutor's office says it will seek to have the charges against them upgraded to second-degree murder.