William Cierzan, then 58, was reported missing in January 2017. When his wife came home that night, she found his wallet, keys and other personal belongings in the home but he had disappeared.
Investigators later found blood in the home.
On Tuesday, the Los Angeles County Sheriff's Department said Daniel Cierzan, 24, had been arrested in connection with the disappearance and murder of his uncle.
William's Cierzan's remains have not been located.
Investigators did not immediately disclose what led them to Daniel Cierzan or his possible motive for the alleged killing.
Authorities were planning to file murder charges in San Fernando court on Tuesday.
At a 2017 press conference, William Cierzan's wife described the day of his disappearance - Thursday, Jan. 26, 2017.
Linda Cierzan said she had just spoken to William around 4 p.m.
"He was happy," she said. "He was telling me he was making dinner because he likes to cook now, and that he had a good day watching golf."
When she got home around 7 p.m., his personal belongings were there and dinner was on the stove. But he was gone.
Valencia man reported missing in January 2017