Months after his bill to combat auto burglaries died in Sacramento, state Sen. Scott Wiener will once again propose legislation he said will make it easier to prosecute defendants accused of breaking into vehicles.

Wiener, D-San Francisco, wants to change the law that requires prosecutors to prove a car’s doors were locked when the offender broke in for the crime to be charged as a felony burglary rather than misdemeanor theft. Getting victims to testify that they locked their doors is an often-fruitless struggle for the San Francisco district attorney’s office because many victims are tourists from out of the state or country.

Wiener has proposed adding “or when forced entry is used” to the state penal code so that a smashed window can qualify as evidence for a felony prosecution thereby reducing the need for a victim to show up and testify.

San Francisco has been overwhelmed by a surge in auto burglaries in recent years. Flanked by the city’s police chief and district attorney, Wiener announced his latest effort to change the law at a news conference Monday at Alamo Square — a notorious hot spot for car break-ins.

“We’ve seen an explosion of auto break-ins in San Francisco,” Wiener said. “The reality is that when people’s cars are broken into it has real impact on their lives. This is the most amazing city in the world, San Francisco, but it is not always easy to live here.”

Wiener will introduce the bill when the Legislature reconvenes Monday, essentially mirroring his effort earlier this year to pass SB916, which died in the Senate’s Appropriations Committee in June.

San Francisco District Attorney George Gascón, a supporter of the previous bill and the new one, brought the idea to change the law to Wiener last year, saying he was hamstrung in prosecuting the limited number of cases that get presented to his office.

“It’s commonsense legislation,” Gascón said. “It’s not widening of any net. It’s simply a loophole that needs to be closed in order to be able to help us deal with the organized rings that are victimizing so many people in our communities and other communities around the state.”

The proposed legislation comes as the number of auto break-ins has exploded in San Francisco over the past five years, with other cities in the Bay Area and around California seeing similar upturns. San Francisco hit an all-time high last year when there were more than 31,000 reported smash-and-grabs — or roughly 85 a day. The scourge has captured the attention of city leaders and police, who have initiated various strategies to fight the epidemic.

The efforts may be paying off, too. San Francisco has seen a 16 percent decline in the crimes so far this year, according to the latest statistics provided by the Police Department. The city’s Northern District, which includes Alamo Square, has seen a 21 percent decrease in the crimes, compared with the same period last year.

Police Chief Bill Scott has explored numerous ways to combat the problem, ranging from adding dedicated foot patrols, assigning officers at district stations to focus on property crime, and working with other city agencies to put warning signs in the city’s worst neighborhood for the crimes.

“We’re doing everything in our power,” Scott said. “This legislation is another step, and I think it will help us.”

Catching people in the act, however, is especially challenging, and police typically make an arrest in only about 2 percent of cases. The Police Department, though, said arrests and citations for vehicle break-ins are up 31 percent through the end of October, compared with all of 2017.

Public Defender Jeff Adachi, whose office ends up defending many of those arrested for car break-ins, said the idea that the legislation would significantly reduce auto burglaries is “pure fantasy.”

“I talk to a lot of folks, and a lot of people are doing it out of survival,” he said. “If you’re doing it for basic survival, the way to get out of that line of work is to address the root cause so they’re not out there doing it.”

Wiener hopes his bill will have more success now that there there will be a new chair of the Appropriations Committee — where many bills are killed in closed-door sessions before they even go to a vote on the Senate floor.

San Francisco Supervisor Vallie Brown, whose District Five includes Alamo Square, said she will introduce a resolution asking the Board of Supervisors to support the state bill in hopes of raising its profile and getting it out of committee in Sacramento.

“I can’t walk through San Francisco or my district without seeing the evidence of car break-ins, broken glass everywhere,” she said. “It’s really frustrating.”

Evan Sernoffsky is a San Francisco Chronicle staff writer. Email: esernoffsky@sfchronicle.com Twitter: @EvanSernoffsky