In his chilling Facebook livestream, which was later re-posted on YouTube, Valentine acknowledged that the violent chain of events he started could end in his own death.
"Pleasure knowing all y'all," he said.
"I've been very sick for months. And this is something that I could not help. So I don't know if I'm gonna make it where I'm going, but if I don't, I wish all of you a good life."
Police in Norlina, a town of 1100 people about an hour east of Raleigh, spent yesterday and today trying to unravel what caused Valentine allegedly to kick in the door of his ex-wife's single-storey home and open fire - and then admit to the crime on social media.
But more than anything, they want to find Earl Valentine.
Authorities from the FBI and the US Marshals Service have joined local and regional law enforcement agencies in a manhunt stretching from Virginia to South Carolina, Norlina Police Chief Taylor Bartholomew told the Washington Post.
Bartholomew said Valentine was carrying a pistol and a shotgun and is considered "extremely" dangerous.
He said he talked to Valentine on the phone and described him as "cold and callous," saying he showed no remorse for the shootings.
"For somebody that had just done something like that, he was calm but he was aggressive," Bartholomew said. "He was trying to pump me for information. His main focus was to make sure his ex-wife was dead."
Bartholomew also quoted Valentine as saying that he wouldn't be taken alive and that he planned to kill his in-laws, then himself.
Keisha Valentine and her teenage son had moved to Norlina nearly nine months ago to get away from her abusive ex-husband, Bartholomew said.
Pleasure knowing all y'all
A year-long domestic violence restraining order she was granted had expired last month. But the police chief said there's evidence that Earl Valentine had exchanged heated words with his ex-wife's family on Facebook.
Still, it's unclear what prompted the assault on Hyco Street.
At about 1.30 am local time, Earl Valentine burst through the front door of the house and marched to his ex-wife's bedroom, Bartholomew said. Keisha Valentine leaned against the door, trying to keep him out, but he managed to shoot her anyway.
Their son, awakened by the commotion, confronted his father. But the teenager fell to the floor and was shot in the chest.
Before he died, he called police and told them what had happened.
Earl Valentine faces a first-degree murder charge in his son's death, Bartholomew said.
Since Facebook Live launched in April, millions have used the service to offer a glimpse into the big moments and small details of their lives.
The view isn't always pretty. The nascent live-streaming service is raising philosophical questions about the power of unfiltered Internet video that can reach millions instantly.
SUSPECTS USING FACEBOOK LIVE
1 Earl Valentine is the latest example of a person using Facebook Live to discuss a violent act - or to showcase the act itself.
2 In June, Larossi Abballa, a terrorism suspect accused of killing a French police captain and his partner in their home, broadcast the aftermath of the attack on Facebook Live.
3 A month later, a Georgia mother went on her daughter's Facebook account to broadcast herself beating the teenager - punishment for posting sexually explicit pictures on the site.
4 A July shooting in Norfolk that injured three men was inadvertently captured on Facebook Live.
5 after police in Minnesota fatally shot Philando Castile during a traffic stop in July, his girlfriend opened Facebook and began livestreaming the aftermath.
