The unidentified woman was arrested for felony hit-and-run, assault with a deadly weapon and felony manslaughter. She is being held at Lynwood Jail, police said.
The arrest comes days after the suspect vehicle was found.
On June 17, Gennady Bolotsky was fatally struck while walking in a crosswalk at Magnolia Boulevard and Wilkinson Avenue.
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He was walking his beloved dog Leelah, who was his companion after his wife of more than 50 years passed away.
Family members said the vehicle in the hit-and-run was a GMC Sierra.
Surveillance video shows the Sierra hitting the elderly man and then running over his body.
Family members had been searching for video evidence and witnesses to help them find the suspect.
"The witness who saw the accident has not come forward yet," said granddaughter Adriana Bolotsky. "Judgment aside, we just need you to come forward and ID this person so we can make our world a little bit safer."
Neighbors said accidents happen at this intersection all the time. In fact, 15 years ago, Gennady Bolotsky was hit by a car in the very same spot and survived.
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"He was supposed to live to 100 or more. At 91, he had more energy than a person half his life," said the victim's son, Michael Bolotsky.
The city of L.A. was offering up to a $50,000 reward for information leading to the suspect.