Video showed the owner and two other women struggling several minutes in vain to pull the dog off the sea lion. As his daughter screamed and cried, Kelly arrived and grabbed the collar. He shook the dog's head until it released the bloodied mammal, which later died.
Kelly is married to former U.S. Rep. Gabrielle Giffords, who was wounded in a shooting in Tucson, Ariz., in 2011. His daughters, Claudia and Claire, are from a previous marriage.
Laguna Beach police said they did not plan to press charges because it did not appear the owner was at fault in the attack Saturday, Capt. Jason Kravetz said Tuesday. The bulldog mix was leashed and legally on the beach below the exclusive Montage Resort.
A necropsy was performed at the Pacific Marine Mammal Center and results were turned over to the National Marine Fish Services, a spokeswoman for the marine mammal center said late Tuesday. Attempts to contact a spokeswoman at that agency did not succeed because her voicemail was full.
In addition, Laguna Beach police checked with Texas authorities, where the dog and his owner live, and found Shiner had a clean record. Kravetz said there were no prior attacks or even any nuisance calls.
If there had been a history of aggression, authorities could have taken action against the dog.
The National Oceanic and Atmospheric Administration also does not expect to take legal action, spokesman Jim Milbury said.
"We will have to wait for all the facts to come in, but it appears to be an unfortunate accident," he said.
Federal law protects marine animals. The state has no jurisdiction, a spokeswoman said.
Earlier in the day Saturday, officers had removed the same sea lion from a storm drain, Kravetz said.
"This is a regrettable and traumatic incident for the animals and the people involved," said Madeline Bernstein, president of the Society for the Prevention of Cruelty to Animals Los Angeles. "Perhaps this will lead to more research and recommendations for peaceful coexistence between domestic animals and local wildlife."
Chasing, hunting or attacking animals like cats and squirrels comes naturally to some dogs, People for the Ethical Treatment of Animals said in a statement. In this case it was a vulnerable sea lion.
If the dog has not shown any other signs of aggression, the family should take new precautions and do all they can to make sure no future incidents occur. "But they should not punish the dog," the statement said.
Giffords was not present during the attack, according to a spokeswoman for the gun control advocacy group the couple recently started.
"Mark was alerted to the situation and came to the beach himself," said Jen Bluestein of Americans for Responsible Solutions.
Gun advocates seized on the incident to criticize Kelly, who has called for background checks for gun buyers.
Several people suggested on his Facebook page Tuesday that background checks might also be considered for dogs whose owners can't control them or those that are a threat to the public. Kravetz said he had gotten several similar calls throughout the day.