New video has emerged showing the vicious gang beating which led to the death of a Las Vegas teenager.

The victim, 17-year-old Jonathan Lewis, appears to throw the first punch in the recording, prompting a mob of students to set upon him and start punching and kicking in an alley near Rancho High School on Nov. 1.

A family member of one of the four teens charged with murder over the assault also claimed to The Post a knife was present during the incident.

In the chaotic new video a figure in a white shirt can be seen lunging for another person which a family member of Gianni Robinson, now facing murder charges, claim is Lewis and shows he instigated the fight.

The video also shows a second student, who has not been publicly identified, attempting to run away from the mob and being stopped.

“Jonathan Lewis’ friend told Gianni that he wanted to stab and kill someone in their group,” said the family member, who requested to remain anonymous.

“Gianni didn’t even know Jonathan Lewis, but they claimed someone took Jonathan’s wax pen a week or two [before the fight]. That’s how this whole thing started.”

Lewis was rushed to hospital and placed on life support after being stomped by the group. He died six days later from his injuries.

The new video still lacks the full context of what led the two pupils and the gang to be facing off in the alleyway.

Las Vegas Metropolitan Police have so far arrested nine teens, ages 13 to 17, in connection to Lewis’ death.

Clark County Unified School District officials declined to comment on the video or whether a knife was involved in the fight. Las Vegas Metropolitan Police officials also declined to answer questions due to it being an ongoing investigation.

Gianni’s family member said the high school junior was confused as to why he was being blamed for stealing Lewis’ wax pen as he was absent from school for weeks before the incident because of a family issue.

They also claimed he and other members of the group had tried to get away from Lewis and his friend before the fight.

Gianni’s family member said the high school junior was confused as to why he was being blamed for stealing Lewis’ wax pen as he was absent from school for weeks before the incident because of a family issue.

“They wanted to stay as a group because Jonathan Lewis and his friend said they had a knife and wanted to stab someone in Gianni’s group,” the family member claimed.

Lewis eventually caught up to them and allegedly approached Gianni, demanding the whereabouts of his wax pen, the source claimed.

Gianni told Lewis he did not take his wax pen, a portable vaporizer used to smoke cannabis, and then another boy confronted Jonathan.

In the extended footage of the fight obtained by The Post, Lewis exchanges words with that teen before he appear to land a punch on the boy, Gianni’s family member claimed.

“They were all standing around seeing what was going on and that’s when Jonathan Lewis started swinging,” the family member said. “And once the group went over there, Lewis’ friend pulled out the knife and started trying to stab at people.”

In the footage another boy can be seen attempting to get away from the crowd and then being stopped, but it is not clear enough to show if he has anything in his hands or if a knife was present.

Lewis’ father, also named Jonathan Lewis, claimed in a GoFundMe post his son died trying to save his friend, who allegedly was put in a trash can by other students.