Los Angeles (CNN) -- Veth Mam had never been to Fullerton, California, until the early morning hours of October 23, when he began recording the arrest of a friend on his iPhone camera.
Instead of documenting what Mam described as a case of excessive force, the 31-year-old factory worker was himself arrested and charged with assaulting a Fullerton police officer.
On Friday, Mam filed a civil lawsuit, claiming that officers falsely arrested him, conspired to violate his civil rights and committed perjury during his misdemeanor trial. Mam, who lives with his girlfriend in nearby El Monte, was acquitted of battery against an officer and resisting arrest last month.
"They lied and tried to cover it up, and I have been very traumatized by this," Mam said during a news conference at his attorney's office in Los Angeles. Fullerton is about 25 miles southeast of downtown Los Angeles.
His attorney, Garo Mardirossian, said the iPhone video by Mam clearly contradicted the police report and served as a "powerful piece of evidence" that eventually exonerated his client.
"The existence of the video was disclosed nearly a month after the officers filed their police reports," Mardirossian said.
On Friday, Fullerton police spokesman Sgt. Andrew Goodrich reiterated a statement that acting Chief Kevin Hamilton has launched an internal affairs investigation into the incident. That earlier police statement also said "there is a strong possibility that we arrested the wrong person that night (Veth Mam)."
Added Goodrich on Friday: "There's a pending lawsuit, and there's not much we're commenting on."
Since the incident, Mam said, he is afraid to go anywhere in public and fears for his safety. His civil lawsuit identifies the Fullerton police chief, the City of Fullerton, five Fullerton officers and 10 other unidentified defendants.
The civil action against Fullerton police was prompted, in part, by the recent death of a homeless man after a violent confrontation with police July 5.
Mardirossian said one of the officers in the Mam incident was also involved in the death of Kelly Thomas, a diagnosed schizophrenic.
In that incident, which authorities say was also captured on videotape, six officers responded to reports of a man reportedly attempting to break into cars near a bus depot, according to police.
Thomas, 37, died five days after what the Orange County district attorney has called "a violent and desperate struggle" with Fullerton police.
How Fullerton police officers write their reports has become a matter of controversy, because in the Thomas case, officers were allowed to view a videotape before filing their reports, Mardirossian said.
Mardirossian is also representing Thomas' father, Ron, who is alleging that his son was a victim of police brutality and has notified Fullerton city officials that he plans to pursue legal action against them.
Mardirossian said his office was contacted by an unidentified civilian who witnessed the Thomas arrest and recognized one of the officers seen arresting Mam in the iPhone video, which released on YouTube.
Fullerton police have declined to confirm Mardirossa's accusation that one of its officers was involved in both cases.
Mardirossian said the suit will support his claim that the Fullerton Police Department engages in a "pattern or practice" of civil rights violations.
On Tuesday, the Fullerton City Council approved the hiring of an independent consultant to reform the city's police force and review the Thomas incident, a spokeswoman said.
After a public hearing of residents angry about the death of Thomas, the City Council voted 5-0 to award a one-year contract to Michael J. Gennaco to examine the police department's policies and practices. Gennaco has said he will look at how Fullerton police officers wrote their reports only after watching the videotape.
Gennaco told the council he will begin investigating the death after the Orange County District Attorney's office completes its own inquiry into the incident. Gennaco is currently chief attorney for a civilian oversight committee created by the Los Angeles County supervisors to monitor the sheriff's department.
Since the Thomas incident, the six officers have been placed on involuntary paid administrative leave, and city officials haven't released their names.
Police Chief Michael Sellers has taken a paid medical leave, and two of the city's five council members have called upon him to resign.
Meanwhile, there are two external investigations into the death, by the FBI and the Orange County district attorney's office. The FBI is looking at possible civil rights violations.
Also, residents notified the city that they are going to start a recall petition drive for the other three members on the city council: Mayor F. Richard Jones, Mayor Pro Tem Don Bankhead and Councilman Pat McKinley. The mayor and mayor pro tem positions are one-year terms rotated among the five council members, officials said.
CNN's Irving Last and Marie Malzberg contributed to this report.