ST. JOHN'S, N.L. -- The Newfoundland police officer who shot and killed Don Dunphy at his home on Easter Sunday 2015 says he would have taken backup if he had known about an old RCMP file cautioning violence.

Const. Joe Smyth told an inquiry Tuesday into the killing that he wasn't aware of the file dating back to 2001 and updated in 2005 on charges against Dunphy, which were later dropped, for marijuana possession and uttering threats.

He said he requested a background check through his Royal Newfoundland Constabulary's communications system as he headed to Dunphy's home in Mitchell's Brook.

He told the inquiry that he was surprised to learn he would have had to ask for a separate RCMP search to learn of the caution.

Smyth said such a red flag -- even though Dunphy had no criminal record -- would have prompted him to take along another officer to the home on St. Mary's Bay.

Smyth said he saw a big sign outside Dunphy's small, rundown place describing it as a "poverty house since 1984." That was the year Dunphy, a former truck driver, was pinned against a vehicle and crushed on a construction site. He was permanently injured and fought for decades after that with workers' compensation.

The sign also warned political types to stay away.

Still, Smyth said he didn't reconsider his decision to go alone.

He told the inquiry the unkempt state of the house, shrouded with overgrown trees, made him wonder about Dunphy's mental health.

"I'm feeling empathy for him," along with a "heightened level of awareness," Smyth said.

Dunphy wasn't home when Smyth first arrived at about 1:30 p.m. and he had not reached him by phone.

He decided to visit the closest neighbour, who turned out to be Dunphy's brother Dick and his wife Debbie. It was Debbie Dunphy who had filed the uttering threats charge against Don Dunphy more than a decade earlier, resolving the matter with a peace bond.

She told police after the shooting that Dunphy had once said he'd "beat the head off" her for telling his only child, now 28-year-old Meghan Dunphy, that he needed mental help.

Meghan Dunphy has testified that he was a good father who raised her alone from the age of three after her mother died of apparent complications from diabetes. She and her father remained close and spent Easter Sunday brunch out together before Smyth showed up unannounced just after Dunphy returned home.

Smyth made the visit after then-premier Paul Davis's staff had flagged a tweet by Dunphy, who often aired his frustrations on social media. Smyth says he found some of Dunphy's tweets "aggressive" and not based in reality but did not consider them, or Dunphy, to be any serious threat.

He said he did not speak to Davis about Dunphy that holiday weekend as it was too early in his risk assessment.

Smyth also said he at first had Dunphy confused with the dirt bike riding gibberish rapper Donnie Dumphy. Dumphy is a comic character, a hit on YouTube and star of the movie "Donnie Dumphy: How to be Deadly."

Smyth, 38, said he went alone to Dunphy's home to build "rapport." Taking along a uniformed Mountie -- Mitchell's Brook is in RCMP jurisdiction -- could have sent an intimidating message that was not intended, he said.

Smyth is expected to testify Wednesday about the actual shooting. He has told police he shot Dunphy once in the chest and twice in the head when he suddenly aimed a rifle at him after the conversation grew heated.

Smyth told the inquiry that Dunphy became increasingly agitated and was insulted when Smyth refused to sit on his couch during the visit because of cat hair, and then commented on the state of his house. Dunphy also wanted to know who had sent him, asking what an RNC officer was doing out of jurisdiction.

Smyth disputed the RCMP timeline of events, especially the suggestion that he waited 12 to 14 minutes after shots were fired to call police and request paramedics. In fact, he says he called for help within two to three minutes.