COLLIN COUNTY, TX -- Authorities are still unsure what started a Ladonia house fire that killed a Collin County Sheriff's Deputy and his wife. While investigators continue to search for answers co-workers and friends are trying to cope with their loss.

"You were one of my biggest supporters during the roughest time of my life. He was such a great guy. One of them said I never remember one time when he wasn't friendly or helpful," Asst. Chief Deputy Charles Adams said.

Those are some of the Facebook posts friends of Deputy Richard Fields wrote after they learned he and his wife Rebecca were killed when their house caught fire early Sunday morning.

"Very sad it just made me sick," Adams said.

Collin County Assistant Chief Deputy Charles Adams says he worked with Fields for about 18 years and his death leaves an empty space they will never be able to fill.

"It's just like a second family, you know, you spend 8 hours a day with somebody 5 days a week. You really miss them," Adams said.

Those who worked with Fields say there are not enough positive words to describe their friend.

"He was a character. He was very liked by all of his co-workers. He was always pleasant to be around. He always made you laugh," Adams said.

"I would like people to know that he was a wonderful family man, a wonderful kind and caring person, willing to help anybody with anything at any time, " Collin County Sheriff Terry Box said.

"Even if he didn't like you he'd give you the shirt off his back if he'd thought you needed it," Adams said.

Adams says Fields worked numerous positions at the sheriff's office, but was currently working with troubled juveniles.

"They called him papaw. That's just what they nicknamed him just because he worked so well with them," Adams said.

Adams says Fields's closest friend at the sheriff's office has been assisting the family.

Sheriff Donnie Foster says the State Fire Marshal is working with them to determine what caused the fire. He says it does not appear to be suspicious, but the fire marshal says it could have been started by a lightning strike.