SAN JOSE — Sheriff Laurie Smith is lashing out at what she called an accusation that an inmate brawl at the Santa Clara County Main Jail was induced to champion her recent decision to personally purchase surveillance cameras that recorded the melee.

In a scathing letter Friday to LaDoris Cordell, a retired judge who heads the county’s civilian jail-reform commission, Smith bristled at the purported insinuation the fight was readily preventable and that jail staff knowingly stoked tensions by letting rival black and Latino inmates congregate. Smith called the accusation “a lie,” tantamount to accusing her agency of criminality.

“As an elected official, I can take your political attacks, it comes with the territory and I’m accustomed to them. However, it is disgraceful that you would accuse my deputies of participating in a criminal conspiracy,” Smith wrote. “Correctional deputies risk their lives daily and conducted themselves honorably and professionally during yesterday’s incident. They deserve better.”

Cordell fired back Friday evening in her own written response, characterizing Smith as being overly defensive and saying she never implied criminal conduct by jail staff.

“I have done no such thing,” Cordell wrote, later stating, “Sheriff, methinks you doth protest too much.”

Hours after the Thursday jail fight, Cordell voiced concern over the fight, a day after Smith announced the camera purchases and had some of them installed in the pod where the fight broke out.

“If in fact, correctional officers knew that on that pod or in that unit there were groups who didn’t get along, be they along racial lines or whatever,” Cordell told NBC Bay Area on Thursday. “I was told repeatedly they’d never let them out because it could lead to a fight and someone could get hurt.”

Smith noted a ban on racial segregation in the jail, and revealed the investigation thus far has found the initial two-man fight that sparked the larger brawl was over money, not race.

In her letter, Smith also objected to Cordell asking a consultant to the Blue Ribbon Commission on Improving Custody Operation to launch an investigation into the fight, and called it a potential obstruction to the existing criminal investigation. Cordell said her request was strictly an informational inquiry so that the commission could use the fight to inform future reform.

Smith ended her letter by declaring she is making a public-records request for all of Cordell’s emails and other correspondence involving the jails since she was appointed to head the reform commission last fall.

“The public deserves to know the motivation behind your actions. I hope that you will embrace transparency,” Smith wrote. “I hope you will refocus on assisting the county in finding solutions instead of manufacturing headlines for yourself.”

Cordell’s response was to assert that it was Smith who asked the judge to head the commission, and that it was Cordell who made transparency an imperative upon its formation. She also stated that her emails to the commission and county staff is already viewable on the commission’s website, save for privileged correspondence with attorneys.

The brawl was reported about 3:10 p.m. Thursday in the maximum-security housing pod of the Main Jail on West Hedding Street and involved upward of 30 inmates, prompting a lockdown of the entire facility. Footage released by the Sheriff’s Office shows the melee began with two people and spread to the rest of the pod during scheduled recreation time for half of the unit’s 60-man population.

Authorities said the melee amounted to a series of fist fights and that no weapons appear to have been used by the combatants; about 20 jail deputies broke it up in part by using pepper spray. No one suffered any serious injuries.

Both Smith and the head of the Santa Clara County Correctional Peace Officers Association said the video of the fracas highlight the everyday hazards jail deputies and officers face securing the embattled jail.

“We look forward to a full investigation and we condemn any reckless conduct that endangers officers and inmates,” Union president Julio Alvarez said.

The fight occurred on the same day a judge ruled that a trial could proceed against three jail deputies charged with murder in the beating death of mentally ill inmate Michael Tyree in a jail cell in August. The case was a catalyst for a host of proposed jail reforms and the formation of the county’s civilian-led reform commission.

That Thursday’s fight was captured on cameras appears fortuitous: Smith just announced Wednesday that after learning installing long-recommended surveillance cameras in housing areas at the Main Jail would take as many as two years and cost upward of $20 million, she went to Costco and purchased a dozen high-definition surveillance cameras, putting the $761.24 tab on her personal credit card.

“We don’t have cameras in any of the other housing areas,” Smith said in a news conference about two hours after the fight. They only went in last night. It’s interesting that it happened here.”

Staff writer Jason Green contributed to this report. Contact Robert Salonga at 408-920-5002. Follow him at Twitter.com/robertsalonga.