An 18-year-old Sonora man was arrested Sunday on suspicion of brutally attacking a 14-year-old victim during a party at an abandoned sawmill on the 300 block of Hospital Road.

The arrest followed a week-long investigation by the Sonora Police Department, who learned that a group of minors and the suspect had trespassed into the old abandoned silos to consume alcohol and party on Feb. 10, he said.

Rogers did not know if the suspect and victim were classmates or if they knew each other, but identified that “alcohol was definitely a factor” in the incident.

During the argument, the victim was seated on an elevated “shelf-constructed type area” and was pulled down to “free-fall” several feet to the ground, Rogers said.

The victim was then punched several times in the face and kicked in the head, causing the victim to lose consciousness.

Rogers would not say if the victim was male or female because the investigation is ongoing.

Emergency services were not called to the scene, he said, but the victim sustained serious injuries and later sought medical attention.

The Sonora Police Department was notified of the assault on Feb. 12 by a witness while an officer was investigating another case, Sgt. Chris Rogers said.

Because the victim didn’t reported the incident, he said, the investigating officer was required to gather the facts by identifying the involved parties and then “by interviewing different witnesses to get a sense about what occurred.”

From the multiple witnesses who gave statements, the officer soon learned some of the details and the name of the suspect, he said.

The suspect was found, interviewed and arrested on Sunday, he said, but the investigating officer was still “tracking down” additional witnesses and seeking to obtain statements from them.

Kaliem Sage Campau, 18, of Sonora, was booked on suspicion of battery with serious bodily injury and assault with a deadly weapon with possible great bodily injury about 3 p.m. on the 24100 block of Italian Bar Road in Columbia.

Rogers said that Campau was charged with assault with a deadly weapon because “your shoes or feet are actually considered weapons” and they had been used to assault the victim in a vulnerable area where he could sustain a serious head injury.

Campau on Monday remained in custody of the Tuolumne County Jail on $50,000 bail.

Contact Giuseppe Ricapito at (209) 588-4526 or . Follow him on Twitter @gsepinsonora.