More than a month after he was attacked while taking a walk around his Sacramento suburb with a Sikh friend and neighbor, 78-year-old Gurmeh Atwal passed away on Friday afternoon from injuries he sustained in March. Police are still trying to determine whether the attack was a hate crime.

Atwal’s friend Surinder Singh was shot and killed on March 4 during the pair’s regular evening stroll in their neighborhood of Elk Grove, near Sacramento, California. Singh, who was 65, died on the sidewalk. Atwal was shot twice and had been on a ventilator since the attack, the AP reported.

Police were unable to find any motive, and the local Sikh community fears that the attack was motivated by Islamophobic hatred. In the wake of September 11, many Sikhs have been swept up in the racialized anti-Muslim and Arab hysteria that continues to rage across the country, and become targets of hate crimes and discrimination as a result.

The Los Angeles Times reported that the two men were attacked just months after a Sikh cabdriver in the Sacramento area reported being attacked by two men who yelled anti-Muslim slurs. Two suspects have been arrested and charged.

“It’s a horrible shock,” Sikh community leader Amar Shergill told the Los Angeles Times. “Although we were hoping he would overcome the injury, the doctors had told us that he was in danger. It’s important for all of us now to rely on our faith as a community and as families to make it through this difficult time.”

No one has been arrested, and police have been unable to establish any other motive.