She fell to the ground, struck by a bullet, the victim of what police say appears to be a random killing.
The man accused of firing the deadly shot -- 45-year-old Juan Francisco Lopez-Sanchez -- is an undocumented immigrant, a repeat felon who has been deported five times to Mexico, according to immigration officials.
It would have been six, a federal law enforcement source told CNN, except authorities in San Francisco wanted him on a drug-related warrant.
So U.S. Immigration and Customs Enforcement, which had Lopez-Sanchez in its custody in March after his release from federal prison, turned him over to San Francisco deputies. ICE said they requested an immigration detainer, asking that the agency be notified before Lopez-Sanchez was released.
But San Francisco is a city that doesn't honor such requests and the sheriff's department released him. Freya Horne, chief legal counsel to the San Francisco County Sheriff, told CNN that he was let go because there was no legal cause to detain the suspect.
On Wednesday evening, he shot the 31-year-old Steinle at Pier 14 once in her upper body, according to police. He was found about a mile away an hour later and arrested. CNN could not determine on Friday if he has an attorney.
Family: She was loving, smart, beautiful
Steinle's father told the San Francisco Chronicle there was one pop and his daughter fell to the ground.
Video shows several people trying to help the young woman.
"She just kept saying, 'Dad, help me, help me,'" Liz Sullivan, the victim's mother, told CNN affiliate KRON
Steinle, a medical device salesperson, died at San Francisco General Hospital. Sullivan said her heart stopped twice on the way to the hospital and she died during surgery.
"She fought for her life," Sullivan said. "They said how strong she was but they just couldn't save her."
Family members called her loving, smart and beautiful. Her cousin said she loved her mother and father "more than anything."
Several of the dozen or more people on the pedestrian pier took photos of the suspect and showed them to police.
Suspect had seven felony convictions
ICE said it turned Lopez-Sanchez over to San Francisco authorities on March 26 for an outstanding drug warrant. The agency requested an immigration detainer, but Horne said San Francisco officials believe that violates Fourth Amendment rights against unreasonable searches and seizures.
The sheriff's office said, "When Mr. Lopez-Sanchez was booked into the jail, there was no active Immigration and Customs Enforcement (ICE) warrant or judicial order of removal for him."
The department would have returned Lopez-Sanchez if there had been a court order or warrant, it said.
Charges were dropped March 27 but Lopez-Sanchez was held until April 15 while the sheriff's office determined there were no other warrants for his arrest and he had completed his federal prison sentence.
According to KRON, San Francisco's policy on undocumented immigrants "states that a law enforcement official shall not detain an individual on the basis of a civil immigration detainer after that individual becomes eligible for release from custody."
The federal law enforcement source told CNN the sheriff's department "didn't even need to hold him. They simply could have notified that they were going to release him and we would have gotten him."
Police said Lopez-Sanchez last lived in Texas, where he was on probation. ICE said Lopez-Sanchez has seven felony convictions, four for drug offenses. His most recent deportation was in 2009.
He was released from federal prison in March after serving several years for felony re-entry after deportation.
Lopez-Sanchez is in San Francisco County Jail and faces a homicide charge. ICE has requested another immigration detainer.