MIAMI (CBS4) – A video obtained by CBS4 News appears to support a high school student’s claim that he was acting in self defense when he stabbed another student with a small pen knife.

Barbara Goleman High School senior Frank Acosta, 18, is charged with aggravated battery and possession of a weapon on a school campus after the February 7th incident that saw him tangle with fellow student Mauricio Padron, 17.

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According to police sources, the two had argued in the school lunchroom.

The cell phone video of the later, bloody encounter, shows Padron, shirtless and in a fighting stance, waiting in a school stairwell. When Acosta enters the stairwell he appears taken aback, and attempts to back away but is blocked by a crowd of students coming through the doorway behind him.

A few seconds later, Padron, with the physique of a football linebacker, charges the much smaller Acosta, fists swinging. The video shows the pair falling backward through the stair doorway and onto the floor of a hallway.

Padron puts Acosta in a choke-type hold, his arm around the other youth’s neck. It’s not clear when Acosta first cuts Padron with the knife, but at one point Padron gets up, bleeding, and charges Acosta again. Other students finally separate the pair.

The video showed Padron striding down the hallway to the school office, blood running from a shoulder wound and down his back. The wounded student can be heard cursing and hurling slurs.

Acosta’s attorney told CBS4’s Gary Nelson Thursday that the video makes it clear his client was acting in self-defense and should not have been charged, that Padron was the aggressor.

“He rushed him like a bull, started punching him,” said Acosta’s attorney Frank Gaviria. “The video clearly shows the alleged victim was grabbing him by the neck, choking him.”

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A week after the incident, schools police also charged Padron – with battery and interference with education.

In the arrest report on Padron, the investigating officer seemed sympathetic to Acosta, writing that “due to the victim’s (Acosta’s) fear of being seriously hurt or incapacitated, he used the knife in an effort to protect himself.”

Acosta’s lawyer said he doesn’t believe the little knife that Acosta kept on his key ring qualifies as a weapon. The blade was 1 1/2 inches long, about half the length of an average man’s pinkie finger. The knife, 3 1/2 inches long when closed, fits easily in the palm of a hand.

“I would say this was a lifesaver,” Gaviria said, displaying a knife virtually identical to the one Acosta used. “It saved Mr. Acosta’s life. This is a common pocket knife and, as long as it’s used for protection and lawful self-defense, it is not a crime.”

Gaviria said he expected the state will drop both the aggravated battery and weapons charge against his client.

A police source close to the investigation told CBS4 News the pen knife, while against school rules, would not be considered a “weapon” under Florida law.

“Had we confiscated this in a random sweep, we would not have made an arrest,” the police source said.

Attorney Robert Pelier, representing Padron, said the cell phone video of the incident doesn’t tell the whole story. Pelier said Acosta had brandished the knife in the earlier encounter in the cafeteria, and had it out and at the ready before Padron charged him in the stairwell.

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“Mr. Padron had been threatened and was taking action to defend himself,” Pelier said. “The school system is preserving all of the surveillance video of the incident and the full story will be revealed in court. We do not intend to try this case in the media.”