NEWPORT, N.H. — Defense attorneys for a New Hampshire man charged with setting a fire that killed a family of four in 1989 are continuing to challenge evidence that the deadly fire was arson.

Lawyers for 52-year-old David McLeod on Thursday cross-examined fire investigators who concluded the fire at the 8-unit apartment building in Keene was started by an open flame held to a couch in an apartment adjacent to where the family perished.

McLeod is charged with four counts of second-degree murder. He left the state soon after the fire and was not charged until June 2010. Members of the New Hampshire cold case unit arrested him in West Sacramento, Calif.

McLeod’s lawyers are pressing theories that a carelessly discarded cigarette or a candle could have caused the fire.