On Friday, her family filed a federal lawsuit against U.S. Immigration and Customs Enforcement, San Francisco County's former sheriff, the federal Bureau of Land Management and the man who allegedly fired the deadly shot.
"Kate's death was both foreseeable and preventable had the law enforcement agencies, officials and/or officers involved simply followed the laws, regulations and/or procedures which they swore to uphold," the lawsuit said.
On the evening of July 1, 2015, Steinle was walking on a busy pier of the Embarcadero with her father when there was a single popping sound in the air. The 32-year-old medical device sales representative was shot in the chest, a bullet piercing her aorta, according to the lawsuit.
Her father, James, held her in his arms. "Help me Daddy," were her last words to him, the lawsuit said. She died later at a hospital.
The man accused of firing the deadly shot -- 45-year-old Juan Francisco Lopez-Sanchez
-- is an undocumented immigrant and a repeat felon who has been deported five times to Mexico, according to the suit.
The suit, which seeks unspecified damages, names the city and county of San Francisco, former county Sheriff Ross Mirkarimi and the United States "for their failures to perform mandatory duties and/or for the unconstitutional and/or negligent acts and/or omissions of their officers, officials, agents and/or employees."
It also names Lopez-Sanchez, a seven-time felon who had recently been released from county custody and was in possession of a stolen .40-caliber government-issued firearm, said the lawsuit, which alleges wrongful death, negligence and civil rights violations.
"Kate's fate was sealed when a U.S. Department of the Interior, Bureau of Land Management Ranger failed to properly secure and/or store a government-issued firearm while it was left in an unoccupied vehicle in a high auto-theft neighborhood," the lawsuit said.
ICE declined to comment on pending litigation but said in a statement that agency director Sarah Saldaña met with members of the Steinle family last year "to express the agency's profound sympathy for their loss and assert the agency's continued commitment to working cooperatively with law enforcement in California and nationwide to promote our shared goals of protecting communities and upholding public safety."
The Bureau of Land Management declined comment.
Attempts to reach the former sheriff and an attorney for Lopez-Sanchez for comment were not immediately successful.
The suit alleges that the shooting was set in motion in March 2015, when the county and former sheriff issued a memo approving a policy that eliminated communication about undocumented immigrants with immigration authorities. The policy was in "direct contravention" of federal and state laws, according to the lawsuit.
Weeks after the memo's release, the sheriff's department transported Lopez-Sanchez from a federal prison to San Francisco to appear in court on a bench warrant for marijuana possession and sales. The drug case was dismissed.
Immigration officials had a detainer request for Lopez-Sanchez but the sheriff's department released him, according to the lawsuit.
"By prohibiting the notification to ICE necessary for custody, detention, deportation and/or removal of undocumented convicted felons, the March Memo deprived KATE of life and liberty without due process, as required under the United States Constitution," the lawsuit said.
"The March Memo amounts to deliberate indifference to federal, state, and/or local law which safeguarded KATE's constitutional rights and is the moving force behind the constitutional violation of her rights."
Lopez-Sanchez was arrested and charged with the murder on July 6, 2015.
The uproar caused extensive finger pointing
, with Mirkarimi blaming federal officials for not keeping the suspect in custody.