The two 17-year-old girls were riding their e-bikes down a quiet street in a small town on Monday, in the slanting light of a summery fall evening. The girls, Maria Niotis and Isabella Salas, close friends, were with Maria’s family, and they were going to get ice cream.

From down the block, a car came shooting up the street, said Maria’s uncle Emmanuel Niotis. “Next thing you know, there were bodies flying up in the air,” he said.

One twisted bicycle was embedded in the crushed front end of the Jeep S.U.V. The driver fled briefly, prosecutors said. Both girls were pronounced dead at the hospital.

And as word of the driver’s name seeped out, for the girls’ families and friends in Cranford, N.J., heartbreak turned to fury.

The driver, they said, was Vincent Battiloro, also 17, who had been fixated on Maria for months, at least. Maria’s mother told a friend she had called the police multiple times because he had parked outside the family’s house and would not leave. Two friends of Maria’s said he had harassed her. Online, where Vincent has tens of thousands of followers as a video game streamer, he had taunted Maria and her mother a week before the crash, ordering pizzas to their house as a prank.

Prosecutors have not released the driver’s name because of his age, describing him only as a 17-year-old from neighboring Garwood. But a state court database shows that a motorist named Vincent Battiloro received 14 traffic summonses for a crash in Cranford on Monday. One person familiar with the investigation into the fatal crash confirmed that the summonses had been issued in connection with that crash. Another confirmed that the driver was named Vincent Battiloro. Both spoke anonymously to discuss a continuing investigation.

The summonses include citations for leaving the scene of an accident in which someone has been injured, reckless driving, driving without a license and going at least 70 miles an hour on a street with a speed limit of 25. The summonses in Vincent’s name were first reported by NJ.com.

The night after the crash, things took a surreal turn: Vincent was back on YouTube, broadcasting live from his usual perch on a brown sofa.

“What’s going on everybody?” he said breezily. “We’re back with another stream and this one is going to be a little different from the previous ones.”

A few minutes later, he started to explain: “In a neighboring town, unfortunately, two girls were killed in a hit-and-run crash,” he said. “There has been a lot of misinformation going on over the internet. But I will say this: I wish my sincerest condolences to those girls, lost in that tragic accident.” He then said that he was “not authorized to talk about the whole thing,” and moved on.

On local Facebook groups and at a memorial that sprouted at the crash site, people expressed outrage: Why was Vincent free? They wondered if it had something to do with his father being a police officer in another New Jersey town, and another relative being police chief in nearby Westfield. (The Union County Prosecutor’s Office would say later that the driver had been released after questioning on Monday “pending further investigation.”)

On Wednesday, two days after the crash, the prosecutor’s office said the driver had been arrested on two counts of first-degree murder, a charge that entails “intentionally, knowingly, or purposefully” causing someone’s death.

In a statement to Fox 5 New York news after the arrests were announced, the girls’ families said: “This was not an e-bike accident, and it was not a hit-and-run.”

Vincent’s family did not respond to a voice mail message left at their home. Prosecutors declined to say whether the person charged in the crash had a lawyer, and a Union County court official would not release information about the case.

The Westfield police chief, Christopher Battiloro, Vincent’s uncle, wrote in a Facebook post on Wednesday that while the suspect in the fatal crash “is related to me, he is not my son and not a member of my immediate family.” He continued, “As a law enforcement officer, I maintain full faith and confidence in our criminal justice system.”

A Greek Orthodox church in nearby Union overflowed with weeping people at a wake for Maria Thursday night. Her white coffin was draped with a Greek flag. Her mother, Foulla Niotis, who works at a restaurant in Cranford, shook as she spoke. Maria, she said, “wasn’t just my daughter. She was my best friend.”

Maria worked at a cafe and wanted to be a cosmetologist, and Isabella acted in high school and community theater and sang with choral groups, according to the girls’ online obituaries.

Over the course of the week, hundreds of people visited the crash scene to mourn and lay flowers and candles. Leyton Buckley, 16, who said he was Maria’s boyfriend, called her “just the sweetest person.”

“You could have been a complete stranger to her and she’d let you cry on her shoulder,” he said. Leyton was also friendly with Isabella and said she had a contagious sense of humor. “Anytime I was with her I couldn’t stop laughing,” he said.

Tammy Carbajal, who works with Foulla Niotis at the Cranford Station House restaurant, said Ms. Niotis had told her that Vincent would park in front of their house and sit for hours and that the family had called the police about him several times.

Elio Martinez, 17, another friend of Maria’s, said that Maria and Vincent had gone to school together and that she had complained to the principal and the police about him. The Cranford police declined to comment, as did officials at the high school that Elio said Maria and Vincent attended.

Elio shared screenshots with a New York Times reporter of an exchange of Instagram messages in April between him and an account linked to Vincent’s other social media accounts.

In the exchange, Elio told Vincent to stop bothering Maria, who was Elio’s girlfriend then. Vincent threatened to release nude photos of her.

“I’m not leaving her alone until she apologizes to me,” he added. The exchange included nude photos of other girls sent by Vincent to Elio.

“I did it to one girl,” Vincent wrote. “I’ll do it to another.” He added: “Keep running your mouth and I’ll create your girls nudes” right now.

In a livestream three weeks later, Vincent told his followers that he had taken “a hiatus from streaming” because of “ridiculous allegations that this girl is making against me,” that “cops got involved and the school got involved” and that he had been suspended.

While streaming on Sept. 23, Vincent spoke frankly about his hostility toward Maria and her family.

“You all know I have a vengeance against this girl for accusing me of sending porn,” he said.

He added: “I think you’re hungry. We’re going to send you a pizza.” He called Domino’s and ordered two pepperoni pizzas. “It’ll be cash at the door,” he says.

Vincent’s livestream the night after the crash was his last. Fourteen minutes in, he paused to acknowledge his audience.

“I built a great following on TikTok, with 39,000 followers, that I have grown since 2020, and I want to thank each and every single one of you,” he said. “I love you all to absolute death. And regardless of what happens, if you don’t see me streaming for a little bit, you’ll understand why.”

Aric Toler contributed reporting.