In the days after Jazmine Barnes, 7, was fatally shot inside a moving car near a Walmart outside Houston on Sunday morning, police have released just one concrete clue about her killer: an image of a red pickup truck recorded by a surveillance camera near the scene of the shooting.

Authorities believe the gunman, described as a man in his 40s with a beard and wearing a hooded sweatshirt, was driving the truck. The Harris County Sheriff’s Office believes the gunman fired at random into the car in which Jazmine was riding with her mother and three sisters, a 6-year-old and two teenagers. A bullet struck Jazmine in the head, her mother said.

Police said Wednesday they still had not identified the gunman. But the case has drawn the attention of national civil rights activists and fueled speculation that the shooting was racially motivated. The gunman is white, police said, and Jazmine was black.

At a news conference Wednesday afternoon, Harris County Sheriff Ed Gonzalez said officers were pursuing a number of tips they had received, and taking a fresh look at a similar — and still unsolved — shooting that took place nearby in 2017. The department was also increasing patrols amid concerns that the gunman could strike again.

“We’re not going to stop until we solve this case,” Gonzalez said.

Jazmine’s mother, LaPorsha Washington, and her sisters met with Harris County investigators Wednesday morning to help them create a composite sketch of the gunman, said Lee Merritt, a lawyer for the family.

In another effort to garner the public’s help, Merritt and Shaun King, a prominent racial justice activist and a columnist at The Intercept, have offered a $50,000 reward for information leading to the gunman’s arrest. Merritt said they were offering their own money as the reward.

Since the reward was announced, Merritt said he had received several tips from people who said they had seen the same red pickup truck in the area before Jazmine was killed. One person reported seeing a man in a red pickup truck break into a parked car and steal a gun, Merritt said.

He said he had forwarded those tips to detectives at the Harris County Sheriff’s Office.

“We are getting a lot of tips now,” Merritt said in an interview. “The word is out there.”

Gonzalez said he could not confirm details of the tips police were investigating. But he added that the department appreciated the public’s help and would methodically vet all the information it was receiving.

Besides those possible leads, Merritt said there might be a connection between Jazmine’s killing and the shooting of two people nearby a year and a half earlier. On Aug. 30, 2017, a white man in a pickup truck opened fire with an AR-15-style rifle at a car carrying A’Vonta Williams and his then-girlfriend’s family, according to the sheriff’s office and Williams’ mother.

No one was killed but a bullet traveled through Williams’ legs, shattering both of them, his mother, Kisshima Williams, said in an interview Wednesday. Another bullet lodged in the stomach of his then-girlfriend’s grandmother.

After the sheriff’s office faced criticism for not aggressively investigating the shooting, which occurred in the chaotic days after Hurricane Harvey made landfall, authorities announced a renewed effort to identify the gunman. But no one has been arrested.

Gonzalez said investigators were looking into the 2017 case once again “to see if we may have missed anything.” He added that the previous shooting occurred about 6 miles from the site of the more recent attack, though the victim eventually drove to the area where the more recent one took place.

Kisshima Williams said that another son read about Jazmine’s killing Sunday and immediately called her to point out the similarities between the two cases.

“It has to be the same person,” Kisshima Williams said. “It’s too similar.”

She said that A’Vonta Williams, who is now 22, did not want to talk about the shooting but that he also believed the cases were connected.

“I talked to him last night, and it’s rough for him because he’s a young man,” she said. “My son was bedridden for four months.”

This article originally appeared in The New York Times.