Glenda Coca-Romero came to the United States 18 months ago to earn money to support her family, including an infant daughter in Virginia and relatives back in El Salvador.

The 21-year-old found a job at a small Woodbridge grocery and jewelry store. She was working there on a Friday night last month when three men entered and opened fire, killing Coca-Romero and wounding her co-worker.

On Wednesday, Coca-Romero’s father joined law enforcement officials as they asked the public for tips in the unsolved case. As he spoke, Irene Coca held his 10-month-old granddaughter, whom he is now caring for.

“She came to this country, like many others, to fulfill a dream, for the opportunities that are here,” Coca, speaking through a translator, said of his daughter. “She just worked. She didn’t party or do anything like that.”

He described his daughter as a charismatic saleswoman who interacted well with customers at Platanillos Grocery and Jewelry.

The FBI announced a $10,000 reward Wednesday for information about the as-yet unexplained shooting.

A surveillance video and interviews with witnesses indicate that three men rushed into the store Feb. 21 and almost immediately started shooting. Prince William County police said they are not sure whether the men had planned to rob the store, because they spent only nine seconds there and took nothing.

The surveillance video, which was released by police, shows the men dressed in dark, hooded sweatshirts and wearing covers over their faces as they quickly made their way past shelves filled with flowers and snack foods.

Police have said it was unclear how many of the men were armed and how many fired shots.

The 42-year-old worker who was wounded is expected to recover, police said. The store’s owner has said that the injured woman, also a Salvadoran immigrant, and Coca-Romero shared an apartment not far from the store.

The Prince William police’s anonymous tip program, which originally offered up to $1,000 for information about the case, has received many calls about the shooting, according to Officer Jonathan Perok, who coordinates the tip line.

But police have not made an arrest, and they hope that the additional FBI reward will encourage more people to come forward.

“We need to find those responsible for this murder,” FBI agent Michael McGarrity said at Wednesday’s news conference. “Someone knows who did this.”