The Contra Costa County Coroner's office identified the victim as 42-year-old Manuel Gwin. An autopsy will be done later today to figure out how he died.
The Pleasant Hill Police Chief told ABC7 it was a bizarre and disturbing pair of crimes yesterday, but he also emphasized that it was at least somewhat settling to find out these were not random acts of crime.
The one man they believe is responsible is under arrest.
"There's blood trails all around the path I just took," said Pleasant Hill resident Kelly Moran.
Moran noticed the blood outside the back of a house on Mary Drive during her morning walk. She heard the man who used to live there with his now-estranged wife and a couple young children, was arrested for violating a restraining order and setting the house on Thursday afternoon.
The woman who lives there wasn't hurt and called for help.
"Officers responded, fire folks responded, put out the fire and found a gentleman in the backyard, trying to injure himself, trying to stab himself – he actually did stab himself several times. He was stopped from stabbing himself and taken to a local hospital," said Chief Pete Dunbar from Pleasant Hill Police Department.
Pleasant Hill Police say the suspect, 39-year-old Robert Hoselton is at John Muir Hospital, being treated for his stab wounds. Neighbors say for decades this house has had an eerie history for those who've lived there.
"Fires, divorces, tragedies. It's just a bad omen right there," said Moran.
And the situation turned worse after this arson and suicide attempt. A few hours later, just a few miles away, police stumbled upon a homicide in a house on Dorothy Drive.
"Somebody had gone to the house, knocked on the door, got no answer and saw what they thought was blood on the front steps. Officers responded, went inside and found someone deceased," said Chief Dunbar.
Investigators say they discovered a connection between the crimes. The victim of the arson was friends with the murder victim.
The motive is still unclear. But what is known is that such crime, random or perhaps not in this case, is uncommon in pleasant hill.
"In Pleasant Hill, that doesn't happen in Pleasant Hill. That doesn't happen here, so that's shocking," said Moran.
Detectives still have to interview the suspect Robert Hoselton, but they have collected evidence they say, including weapons that connect him to both scenes.