ST. JOHN'S, N.L. -- The Newfoundland police officer who shot and killed Don Dunphy says he didn't intentionally alter the dates of messages on his BlackBerry cellphone, nor did he mean anything derogatory when he called him a "lunatic."

Const. Joe Smyth of the Royal Newfoundland Constabulary was recalled Monday to an inquiry into the April 2015 death for questions about texts retrieved since he testified under oath in January.

Smyth told inquiry commission co-counsel Sandra Chaytor that if dates were altered on messages exchanged on his BlackBerry, he doesn't know how.

"If I was going to do something intentional I would have dropped it in the St. John's harbour," he said.

An initial RCMP search of Smyth's BlackBerry records for the month Dunphy died did not capture several messages because they were somehow re-dated outside that period.

For example, an exchange with Heather MacLean, communications director for then-premier Paul Davis, became dated March 26 of that year. It was missed by the search when, in fact, it happened April 6, the day after the Easter Sunday shooting at Dunphy's home.

Smyth at one point offers to help MacLean with a media scrum Davis was to hold with reporters that day.

Smyth, 38, has testified he shot Dunphy once in the left chest and twice in the head in self defence after he aimed a rifle at him. He went alone to Dunphy's home in Mitchell's Brook after a post on Twitter was flagged "of concern" by staff in Davis's office.

The Mounties investigated the killing, which was in RCMP jurisdiction, and found there were no grounds for charges. Smyth is the only witness.

He testified last January -- before separate deleted BlackBerry messages were recovered and submitted to the inquiry -- that he never considered Dunphy a threat and never got advice on his notes about the shooting.

But in those retrieved BlackBerry messages, Smyth told an unidentified friend the day before the deadly encounter that he had to deal with a "lunatic" who was "threatening the premier."

Smyth said Monday he habitually deleted direct text messages to clear space on his outmoded phone.

He said he used the term "lunatic" after reviewing Dunphy's social media posts over the previous year, including what he described as "ranting" comments.

Dunphy, 58, was an injured worker who frequently aired his frustration with workers' compensation on Twitter.

"I've referred to my own counsel as a lunatic," Smyth said of his lawyer, Jerome Kennedy, drawing laughs from other inquiry lawyers. But Smyth said he would never say it about someone he genuinely thought had mental illness.

"It's not meant to be derogatory."

Smyth also told the inquiry Monday he has no recollection of several texts with RNC Sgt. Tim Buckle the morning of April 6, 2015, about notes Smyth would take to his interview with RCMP investigators later that day.

He said Buckle advised him on wording about use-of-force policy -- not about the facts of the shooting -- and that he did not follow that advice.

Smyth said it wasn't unusual for him to contact Buckle, a close friend, which may explain why he doesn't remember the exchange.

"Me speaking to Tim Buckle has been a matter of routine for the better part of 17 years."

The inquiry is hearing from more than 50 witnesses and is to wrap up later this month.

Commissioner Leo Barry is to report and make any recommendations by July 1. He will not make findings of criminal or civil responsibility but any new evidence could be investigated by police.