The video taken by Paul Murdaugh at the family's dog kennels before he was killed "changed everything" in the case, prosecutor Creighton Waters said, arguing that Alex Murdaugh had the opportunity to kill his son and wife.

Murdaugh admitted that he lied to investigators about his whereabouts on the night that his wife Maggie and son Paul died in June 2021.

The former lawyer acknowledged his voice can be heard in a video that appeared to be filmed at the kennels, where the bodies of his wife and son were found. Prosecutors have used the video to place Murdaugh at the scene of the killings, contradicting his previous repeated statements to law enforcement that he had not been there that night.

Numerous witnesses had testified Murdaugh's voice is in the background of the video recorded by his son at 8:44 p.m. ET on June 7, 2021.

The video shows opportunity, Waters said in his closing argument Wednesday, “being at the scene of the crime when the murders occurred.”

“[It] more importantly [is] exposing the defendant's lies about the most important thing he could have told law enforcement — 'when was the last time I saw my wife and child alive?’ Why in the world would an innocent, reasonable father and husband lie about that and lie about it so early? He didn’t know that [video] was there," Waters said.

CNN's Emma Tucker contributed reporting to this post.

Correction: An earlier version of this post included the wrong description of a video taken at the Murdaugh family's dog kennels.