The family of five children who died when a fire ripped through a North Minneapolis duplex this February is preparing to file a wrongful death lawsuit against the property's owner.

A petition filed in district court seeks to have a retired judge appointed as a trustee on behalf of the family, the first step in a potential wrongful death suit. The family's attorney, Jeffrey Sieben, said they expect to name property owner Paul Bertelson or his company Mission Inn Minnesota as a defendant in the suit -- which could be filed by the end of the summer.

Precisely when the suit will be filed, and whether there will be other defendants, depend on the outcome of a lengthy joint investigation.

“We don’t have any final conclusions now," Sieben said. "So I don’t know what the complaint’s going to look like, specifically.”

Bertelson, who owns Mission Inn Minnesota, deferred comment to the company's attorney Bill Moran.

“At this point we are involved in an ongoing investigation and analysis of the scene," Moran said. "And so I’m really not at liberty to comment on what the intentions are of Mr. Lewis or his lawyers at this point because it is an ongoing process that we’re involved in.”

The nighttime fire stunned the city this winter, taking the lives of children between 18 months and 8 years old. Their father Troy Lewis, who survived the blaze, blamed a lack of heat in the apartment.

While the fire department said the cause of the fire was undetermined, an incident report said it appeared to have started in the same area as a space heater Lewis had recently purchased to warm the unit.

Lewis said he had repeatedly alerted Mission Inn to the heat problem. Bertelson countered that his company did not get calls about heat problems in the unit.

Sieben said a long list of stakeholders, including Mission Inn, the family and insurance representatives, are jointly participating in the investigation. Experts are routinely being flown in from across the country to review evidence.

“We have been to the house several times," Sieben said. "But I believe we’re done there. The items that were removed will be analyzed.”

That's a lengthy process because of all the parties involved. "We have to coordinate all of those schedules so anytime we open a bag of evidence, we are all there," Sieben said.

While he expected the suit to be filed in late summer, Sieben stressed that could change depending on the outcome of the investigation. "I just don’t know what we’re going to find.”

He said they have not reached a conclusion about the finer points of what caused the fire, but know the area where it ignited.

The proposed trustee, retired judge Cara Lee Neville, has not yet been appointed. A hearing on that matter is scheduled for June 26th in district court.

Photo: Fire inspectors were at the home on Colfax Avenue North where five children died in a house fire, Wednesday, February 19, 2014 (Elizabeth Flores)