In a matter of hours, Steinle was dead, and police had arrested an undocumented immigrant who they accused of pulling the trigger.
But Steinle's family has balked at her case becoming the symbol of Republicans' immigration agenda. The attorney defending the suspect in the case says there's more to the story than meets the eye.
And Juan Francisco Lopez-Sanchez, the undocumented Mexican immigrant who's accused of killing Steinle and of repeatedly entering the United States illegally, has yet to go on trial.
Lopez-Sanchez appeared in court on Friday, wearing an orange jumpsuit and a blank expression through most of the proceedings.
Here's the latest on the case:
The trial: Start date unknown
His trial has been delayed a number of times since his arrest. And it's unclear when it will begin.
Prosecutors filed a motion to postpone the trial on Friday. Attorneys on both sides are juggling other cases, and Judge Philip Moscone asked them to return to court next week to give an update on when they will be free to proceed.
Lopez-Sanchez is charged with second-degree murder and pleaded not guilty during his 2015 arraignment.
The case stirred swift controversy after two details came to light:
• Before the shooting, officials in San Francisco, a so-called sanctuary city, had released Lopez-Sanchez rather than turning him over to federal authorities.
His public defender has said there's more to the story.
"There's substantial evidence that it's a complete accident," attorney Matt Gonzalez told CNN. "From our point of view, the bullet ricocheted off the ground."
Prosecutors have painted Lopez-Sanchez as a danger to the public
, arguing that Lopez-Sanchez pointed the gun at Steinle and deliberately pulled the trigger.
"This was an act of random violence," Assistant District Attorney Diana Garcia said in 2015. "And the defendant claimed to have found this gun shortly before just firing it at somebody at close range, shooting an innocent victim in the back."
Gonzalez told CNN it's not uncommon for a murder trial to take a few years to make it to court.
But both sides, he said, are prepared to proceed.
"We're trying to avoid postponement," he said. "I do think all the parties are ready to litigate the case now."
The family: 'I don't know who coined Kate's Law'
Across the country, Steinle's name was back in the spotlight in Washington this month after House lawmakers passed "Kate's Law," a measure that would raise the maximum prison penalties for immigrants caught repeatedly entering the United States illegally.
Her father told San Francisco Chronicle columnist John Diaz last week
that the family supports the measure. But he wishes his daughter's name wasn't part of it. The family, he said, wants space to grieve and doesn't want his daughter's name to be part of a political controversy.
"I don't know who coined 'Kate's Law,'" Jim Steinle told the Chronicle. "It certainly wasn't us."
A Steinle family spokesman declined to comment for this story.
The family filed a lawsuit
in 2016 alleging that San Francisco and its former sheriff were partly to blame for Steinle's death, because officials never notified Immigration and Customs Enforcement when Lopez-Sanchez was released from a local jail in April 2015. City officials have said they're not liable for a former inmate's actions. A federal judge dismissed the family's claims
against San Francisco and former Sheriff Ross Mirkarimi earlier this year.
The family has stressed that their views on immigration policies are nuanced. In a 2015 interview
with the San Francisco Chronicle, the Steinles said they don't oppose sanctuary cities outright.
"We realize that when (then-Mayor) Dianne Feinstein first drafted the policy, the original purpose was to protect law-abiding immigrants to allow them to call and report crimes and go to the hospital," said Steinle's brother, Brad.
Her father, Jim, added: "It was done for all the right reasons. We're a country of kind people and people were being persecuted in Central America. I get what she did and I agree with it."
As for Kate's Law, according to the Chronicle's Diaz, Jim Steinle said he supports the measure on the chance that it could save one life.
"He has no interest in doing further interviews," Diaz wrote, "or otherwise seeing his daughter's name raised by either side in such a charged and often vitriolic debate."
The politics: Case underpins Trump immigration strategy
The Trump administration and supportive Republicans have made Steinle's death, along with other crimes allegedly committed by undocumented immigrants, a central focus of their immigration strategy.
In addition to the namesake legislation, Steinle's death is mentioned in virtually every conversation lawmakers have about sanctuary cities, a catch-all term for jurisdictions that do not cooperate in some capacity with federal immigration enforcement. Attorney General Jeff Sessions mentioned her killing anew on Wednesday during a speech on sanctuary cities in Las Vegas, calling it a prime example of why hardline immigration policies are needed.
"Her death was preventable — and it should have been prevented," Sessions said. "She would still be alive today if her killer had been imprisoned or deported, as he should have been."
Critics of the bill say Kate's Law would aggressively criminalize undocumented immigrants whose illegal presence in the country carries only civil, not criminal, penalties. They also accuse the administration of unfairly and inaccurately portraying immigrants as criminals. Defenders of the bill say any crime committed by an undocumented immigrant is a crime that could have been prevented.
On Friday, Lopez-Sanchez's attorney said "fanning the flames of public outcry" and tying the case to a larger immigration debate doesn't make sense.
In a recent column for the San Francisco Chronicle, he argued
that the attention surrounding the measure could make it harder for his client to get a fair trial.
"Passing Kate's Law as a response to this tragedy is the legal equivalent of invading Iraq in response to 9/11 — a preying upon emotions to further a pre-existing agenda," Gonzalez wrote.
Though the House has passed Kate's Law and a corresponding bill that would defund sanctuary cities and expand requirements for local law enforcement when it comes to immigration, the bills have an unclear future in the Senate, where eight Democrats would have to join the entire Republican majority for the bills to advance.
The administration also has limited ability to go after sanctuary cities on its own, with a federal judge in San Francisco blocking parts of Trump's executive order targeting the cities from going into effect.