VANCOUVER, Wash. — Investigators said Wednesday they believe a Washington father who was sliding into financial ruin deliberately set a fire that blew up his home, killing himself and five of his children.
"The fire was intentionally set," said police spokeswoman Kim Kapp.
Tuan Dao is the only suspect identified.

VANCOUVER, Wash. — Investigators said Wednesday they believe a Washington state father who was sliding into financial ruin deliberately set a fire that blew up his home, killing himself and five of his children.

"The fire was intentionally set," said police spokeswoman Kim Kapp.

Tuan Dao is the only suspect identified.

The Columbian newspaper reported that Tuan Dao's mother answered the door briefly on Wednesday and broke down in tears. "That was my son, you know?" she told the newspaper before closing the door.

The Columbian reported Dao's wife, Lori, and a 13-year-old daughter were away at the time of the fire.

Police said they believe based on evidence that those killed in Sunday's fire were 37-year-old Tuan Dao, 12-year-old Nolan, 9-year-olds Noah and Jacob, 8-year-old Samantha and 6-year-old Nathan.

The names may be officially confirmed in a few days by the Clark County medical examiner's office, which is using dental records, Kapp said.

Tuan and Lori M. Dao filed for Chapter 7 bankruptcy on Sept. 21, 2010. The couple's bankruptcy filing depicts a family once on firm financial footing that began to crumble.

Together they earned $86,000 annually. He was an assistant manager at a FedEx store in Portland, a position he held for 14 years. Lori Dao had spent more than two years as a banker at a U.S. Bank branch in Vancouver.

They cited $158,000 in credit card debt and other debts. The paperwork also disclosed $2,000 in gambling losses. The couple also owed $262,000 on the house that burned, while the property was valued at $179,000.

Their checking accounts were nearly tapped — $50 in one checking account and $700 in another. They estimated an $8,000 refund on their 2010 taxes.

Their largest asset was a $51,165 retirement account.

They took out a second mortgage on the home that burned, but the bank that issued it, San Antonio-based USAA Federal Savings Bank, declined to say when.

Detectives are trying to confirm and corroborate details of Dao's activities in the days leading up to the fire, Kapp said.

A makeshift memorial was put up Tuesday along a chain-link fence. It included a white piece of paper that listed the names and ages of the five children killed in the fire.

The note was signed "From Friends at Hearthwood," an elementary school that's about one-half mile from the home.

The children attended Hearthwood and Harmony elementary schools, and Pacific Middle School in Vancouver.