Isaías Berriozabal-Martinez, 23, of Capulhuac, Mexico, who immigrated to this country three years ago and last fall launched El Compadre, a Mexican eatery in South Philadelphia, died Jan. 11 of unknown causes at his parents' home.

Ben Miller said that his son had trouble breathing at about 7 a.m. He collapsed and could not be revived. There were no obvious previous health problems.

"Our family and friends are grieving today over the death of Isaías. . . . Keep us in your thoughts," his family posted Wednesday on facebook.

The Philadelphia Medical Examiner's Office said the case is pending.

Mr. Berriozabal-Martinez is the son of Cristina Martinez, a celebrated Mexican chef who with her husband, Miller, owns the popular South Philadelphia restaurant South Philly Barbacoa.

With his mother's help, Mr. Berriozabal-Martinez opened his own restaurant, El Compadre, on Oct. 24 at 1149 S. Ninth St., the former site of Los Taquitos de Puebla.

El Compadre was an attempt to capitalize on the popular torta - or Mexican sandwich - that had been pulled from the menu at South Philly Barbacoa earlier last year.

Born in Capulhuac, Mr. Berriozabal-Martinez, who had a 10th-grade education, came to this country three years ago by crossing the border illegally and hiking through the American desert, his father said. He was undocumented at the time of his death.

The younger man dreamed of someday starting a family and buying his own home. In the meantime, he was living with his parents in South Philadelphia.

Before opening El Compadre, he had manned the taco station at South Philly Barbacoa for a year. He also arranged to grind - or nixtamalize - corn into fresh masa for tortillas.

"It's an ancient process," Miller said. "He talked to his aunts in Mexico and brought the machine to Philadelphia."

The move did not go unnoticed by Inquirer food critic Craig LaBan.

"Barbacoa just installed a machine to grind their own corn into proper masa," LaBan wrote on Dec. 29, 2015. "Pretty much every Mexican restaurant in the region is using the just-add-water mix known as Maseca Harina.

"It will be a revelation to taste tortillas made from fresh corn that's been nixtamalized (soaked in alkalized water) and processed fresh for tortilla flour on site."

Miller said his son's hard work was integral to growing the two restaurants. In his honor, El Compadre will stay open.

Mr. Berriozabal-Martinez loved children and enjoyed cooking with fresh ingredients. Besides his parents, he is survived by two brothers and a sister in Mexico.

In keeping with Mexican customs, mourners will gather at 8 p.m. for nine nights of vigils, which started Jan. 11 at South Philly Barbacoa, 1703 S. 11th St., Philadelphia.

A 9 a.m. viewing Monday, Jan. 16, will be followed by a 10:30 a.m. Funeral Mass at Annunciation BVM Church, 1511 S. 10th St., Philadelphia. Burial is in Fernwood Cemetery, Lansdowne.