TRACY, San Joaquin County (CBS / AP) — Members of the Sikh community on Wednesday asked the FBI to investigate the death of a 64-year-old man who was killed during a nighttime walk at a Central Valley park.

A candlelight vigil was held Wednesday evening for 64-year-old Parmjit Singh, who was wearing his traditional turban when he was fatally stabbed Sunday night in Gretchen Talley Park in Tracy.

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The killing came a month after another Sikh man was attacked in a neighboring community.

“We are demanding that hate crime charges be brought” when the killer is caught, said Megan Daly, spokeswoman for the United Sikhs group.

Parmjit Singh. (Harnek Singh Kang/United Sikhs via AP)

Parmjit Singh. (Harnek Singh Kang/United Sikhs via AP)

Police have not determined a motive for the attack but said they were looking into all possibilities. On Monday, they released video of a man who was seen running in the park area around the time of the stabbing and asked for public help in identifying him.

However, investigators haven’t determined whether the man is connected to the killing, police said.

That video was taken from a nearby elementary school. There are surveillance cameras at the park but they haven’t worked for years because they were installed by a neighborhood watch group that has since disbanded, police told a Sacramento TV station.

Singh came to the United States three years ago from India to stay with family in Tracy. He had two children and three grandchildren.

“It’s a terrible time for the family. It’s a big loss for us,” Singh’s son-in-law, Harnek Singh Kang, told The Associated Press Wednesday.

He described Singh as a good man who was involved with the Sikh community and was well-liked among neighbors of all religions.

Singh was “one of the happiest men,” he said.

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Singh walked 2 miles (3.2 kilometers) a day and was killed during his routine nighttime stroll, his son-in-law said.

“I always see that gentleman. He’s very friendly. He always waves at everybody,” neighbor Marlo Soria told KXTV-TV. “It’s sad. We come to this park to bring our dogs. Just to even think that something like this could happen, right here where we live, is scary.”

In the wake of Singh’s death, the family is “terrible. Horrible,” Singh Kang said. “We’re going through a very hard time right now. We need just to capture that monster.”

There is a large population of Indian immigrants, including Sikhs, in the Central Valley, he said, and local Sikhs are afraid that they are being targeted for attacks.

“We are worried that some of the bad people hate us because we are hard-working people and … they think that we are taking their jobs,” he said.

The attack came only a month after an assault on a priest at a Sikh Temple in Hughson, about a half-hour’s drive from Tracy. The priest said a masked person broke two windows of his home on temple property, punched him and told him to go back to his country.

No arrests have been made.

Two Sikh men also were attacked last year in local communities.

A 71-year-old man was beaten, spat upon and had his turban knocked off in Manteca last August. Authorities say robbery was the motive. Two teenagers, including the estranged son of the Union City police chief, were arrested in the attack.

In July 2018, a Sikh man was putting up campaign signs for local Republicans in Keyes when he was ambushed by two men who beat him and spray-painted a neo-Nazi symbol on his truck.

No arrests have been made in that attack.

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© Copyright 2019 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.