The 18-year-old man accused of hitting a UCSB Police officer in the face with a backpack will be held to answer for charges of assault, resisting arrest and causing great bodily injury, a Santa Barbara County Superior Court judge determined Thursday.

Judge Brian Hill presided over the preliminary hearing of Desmond Louis Edwards of Los Angeles, and decided there was enough evidence to move forward with all but one of the charges against him — the charge of mayhem was thrown out.

Edwards is accused of leading law enforcement officers on a foot pursuit along the 6700 block of Del Playa Drive during the unsanctioned, alcohol-fueled event of Deltopia.

When members of the Sheriff’s Department’s Isla Vista Foot Patrol and UCSB Police chased after suspects in a fight, Edwards allegedly ran down the street and threw his backpack, containing a large glass liquor bottle, into the face of UCSB Officer Tony Magaña, who testified Wednesday.

The backpack, which was recovered by Magaña, had a 1.75-liter glass bottle of rum inside and weighed 7.4 pounds, authorities said.

Magaña ended up at the Santa Barbara Cottage Hospital emergency room with a concussion and got 30 stitches by a plastic surgeon for the cut above his right eyebrow, District Attorney investigator Tom Miller testified Thursday. There should be no lasting damage, though there could be a visible scar, according to interviews with his treating physicians.

Dr. David Wyatt, who treated Magana, told Miller in an interview that the hit and impact were similar to a fistfight.

Senior Deputy District Attorney Mary Barron and Deputy Public Defender Mindi Boulet showed security camera footage during the preliminary hearing this week. The pole cameras were temporarily installed along Del Playa Drive for the Deltopia event after some were installed on the UCSB campus in response to several violent sexual assaults.

Authorities believe the arrest — in which Edwards was tackled, punched and handcuffed in a driveway — was the catalyst for the hours-long riots in Isla Vista the night of April 5.

The foot chase started because Edwards was a suspect in a group fight, Isla Vista Foot Patrol deputy Justin DiPinto testified Thursday.

DiPinto testified hearing the sound of a stun gun — the “clack clack clack” of arcing electric current, he said — and seeing the group separate a bit, probably for their own safety from whoever had the weapon.

He and other officers chased two men — allegedly including Edwards — westbound on Del Playa Drive while other suspects ran eastbound. DiPinto crashed into a woman standing in the street, bringing them both to the ground, but then got up and kept running after the two men, he said.

Magaña got close to Edwards and, allegedly, Edwards threw the backpack into his face and kept running.

Right after that, Edwards was tackled to the ground in a driveway by another deputy, DiPinto said.

In response to questioning from Boulet, DiPinto said Edwards was face down with his hands under him when he was tackled, and when he didn’t put them up for police, DiPinto punched him twice in the pack with “distraction blows” to get compliance.

Deputies then handcuffed him, which is when the huge crowd started to gather, DiPinto testified.

People were throwing “anything that could fly through the air” at law enforcement officers, including bottles, bricks and bicycles, he said. Thousands of people had gathered in the area in a matter of seconds, he added.

“The crowd was hostile, they were shouting at us to let him go,” DiPinto said.

DiPinto left to take Edwards out of the area but he could hear other officers being assaulted over the police radio, he said. He could also hear Magana describing the person who had assaulted him: a man of Asian descent in a white shirt, pink shorts.

Edwards is black.

“He’s obviously not Asian but he’s a light-skinned black male adult,” DiPinto said in court.

Sheriff’s deputies have testified to finding identification of Edwards and a friend inside the backpack, along with the liquor bottle.

Judge Hill called Magana’s head injury “significant” but not enough to pursue the charge of mayhem.

Edwards will be arraigned under the revised charges and for now will stay in the Juvenile Hall facility even though he has turned 18. He was 17 at the time of the arrest, but the District Attorney’s Office charged him as an adult.

He is being housed with other juveniles, a probation officer said in court.

Boulet wants to reduce the bail amount and keep Edwards in Juvenile Hall instead of transferring him to the County Jail, but those issues will be decided at a future hearing.

Edwards is scheduled to be back in court July 8. His parents and other relatives were present at this week’s preliminary hearing.

Noozhawk news editor Giana Magnoli can be reached at Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.