Shane Dubyak, 23, of Lakewood was taken into custody Friday after a chase and a foot pursuit from Artesia to Cerritos, according to Los Angeles County sheriff's investigators. A firearm was also recovered.
Detectives launched an investigation after the incident was captured on surveillance video, showing someone shooting the dog Sunday before driving off.
Two possible suspects were arrested Wednesday night, but were later released after authorities determined they were not involved.
Possible suspect in custody in fatal shooting of dog in La Mirada, authorities say
A witness reported hearing two gunshots after he saw a man place something in a sewer in the 16400 block of Phoebe Avenue. The witness then found a dead terrier mix laying on a dog bed.
"It's very disturbing," said sheriff's Detective Mark Christiansen. "There's ways to properly handle old, sick, injured dogs and this isn't the way to do it."
Detectives are asking anyone with information to contact the sheriff's Norwalk station at (562) 466-5419. Those wishing to remain anonymous can call (800) 222-8477.