Mayor London Breed’s plea for mercy for her brother, who is serving a 44-year prison sentence in the death of his girlfriend, was spurned Monday by Gov. Jerry Brown.

Breed’s brother, Napoleon Brown, has spent 18 years in prison for involuntary manslaughter and armed robbery. Breed, a defense witness at his trial, asked the governor in October to commute her brother’s sentence and release him, saying his punishment had been excessive and he had turned his life around in prison.

But he was not among the names included in Gov. Brown’s last scheduled announcement of sentence commutations and pardons. The governor did not seek approval for a commutation from the state Supreme Court, whose permission would be required because Napoleon Brown has multiple felony convictions on his record.

The governor, who had already granted clemency more often than any other governor in modern California history since returning to office in 2011, added hundreds of names to that list Monday, bringing his totals to 283 sentence commutations and 1,332 pardons, which remove convictions from people’s records. Although he did not seek to commute death sentences for any of the state’s 739 condemned prisoners, he granted Death Row inmate Kevin Cooper’s request for new DNA testing of evidence that Cooper claims would clear him of four Southern California murders committed 35 years ago.

Brown did not state reasons for denying clemency to Napoleon Brown or any of the thousands of other inmates and ex-convicts who had submitted applications. They could renew their requests to his successor, Gov.-elect Gavin Newsom.

Napoleon Brown, 46, is in prison for the death of 25-year-old Lenties White, who was hit by a drunken driver while lying on the deck of the Golden Gate Bridge in June 2000. Prosecutors said White was driving the getaway car after Brown and another man robbed a Johnny Rockets restaurant in the Marina district. As she was dying, she told a police officer that Brown had pushed her out of the car and onto the bridge after police pulled them over.

Brown was initially convicted of murder, but a judge found that his trial lawyer had represented him incompetently. He then pleaded no contest to involuntary manslaughter, armed robbery and other charges and was sentenced to 42 years, with two years added later for possessing heroin in prison.

Breed testified at her brother’s trial in 2005, saying she recalled him being at home on the night of the crime. In her Oct. 23 letter to the governor, she acknowledged that her brother’s “decisions, his actions, led him to the place he finds himself now.”

But the mayor added, “Prison is not the place for him to stay clean, for him to make meaningful amends for his crimes, for him to pursue restorative justice.”

Her brother also asked the governor for a sentence reduction, writing that he felt remorse for his crimes and had worked at “battling my addiction and my bad behaviors” in prison programs. He said he hoped to rejoin his family.

A spokesman said Breed declined to comment on the governor’s rejection Monday.

Breed’s letter, written on personal stationery with her title in block letters, raised questions about whether she was trying to use the power and prominence of her office to tip the scales in her brother’s favor. But multiple attorneys and government ethics experts agreed that Breed did not appear to violate any state or city laws in seeking leniency for a family member.

Breed’s letter was sent with similar messages of support from other family members as part of her brother’s application to have his sentence commuted, according to documents reviewed by The Chronicle.

In the past, Breed has been up-front about having a brother in prison, but rarely, if ever, publicly discussed the details of what landed him there. She has often used the narrative of her own difficult upbringing, in public housing in the city’s Western Addition, and the divergent paths she and her brother took in life to illustrate that, with enough support, people can be lifted up out of poverty.

In Monday’s actions, Brown commuted 131 prison sentences, including some life-without-parole terms for convicted murderers who will be able to seek release from the state parole board if they can show they are no longer dangerous. He issued 143 pardons, which erase criminal convictions and make ex-convicts eligible to apply for some types of state licenses, and to possess firearms if their crimes did not involve the use of a dangerous weapon.

A pardon also allows noncitizens who are legal U.S. residents to avoid deportation for a felony conviction. Lawyers said Brown’s actions Monday allowed six Cambodians to remain in the United States. One of them, Sear Un, whose family had fled the mass killings in Cambodia when he was 7, had faced deportation for a 1998 home burglary that netted him $120.

Brown, who opposes capital punishment, did not respond to pleas from six fellow governors, in a recent New York Times column, to spare the lives of prisoners on the nation’s largest Death Row by commuting their sentences to life in prison. But he gave Cooper the opportunity he has sought to win his freedom if new DNA testing exonerates him.

A jury convicted Cooper, now 60, of fatally slashing a couple and two children in a San Bernardino County home in June 1983, near a prison where he had escaped while serving a burglary sentence. A federal appeals court halted his scheduled execution in 2004 and ordered DNA testing of a bloody T-shirt found near the home, but Cooper’s DNA was found on the shirt, and his death sentence was reaffirmed.

A group of dissenting judges, however, said there was evidence that officers had tampered with the test, and that Cooper was “probably innocent.” After years of disputes over the evidence, Brown ordered new DNA testing Monday of the T-shirt, a towel found nearby, and the handle and sheath of a hatchet that may have been the murder weapon.

Brown named a retired judge, Daniel Pratt, to supervise the testing and said the case would be closed, with Cooper’s fate unchanged, unless the tests pointed to a specific person.

“We’re very excited, after so many years of waiting, to be able to show Kevin is innocent,” said Norman Hile, a lawyer for Cooper.

Another notable figure granted clemency was former state school Superintendent Bill Honig, whose 10 years in office ended in 1993 when he was convicted of four charges of criminal conflicts of interest for using funds from his department to benefit a school program run by his wife. He was given a suspended one-year jail sentence and ordered to pay restitution of $274,754.

His trial judge later reduced the felony convictions to misdemeanors. Brown sought to appoint Honig to the state Board of Education in 2011, but Honig withdrew under pressure.

Honig “has devoted much of his life to education,” continues to work with educational organizations, and “has paid his debt to society,” Brown said in granting a pardon.

San Francisco Chronicle

staff writer Dominic Fracassa contributed to this report.

Bob Egelko is a San Francisco Chronicle staff writer. Email: begelko@sfchronicle.com

Twitter: @BobEgelko