Authorities have arrested a 14-year-old girl on suspicion of manslaughter while they investigate her story that she helped her father commit suicide.

The girl said her 56-year-old father, a self-employed electrician, tried to fatally shoot himself Sunday and was near death when she found him, allegedly prompting her to "end his suffering," Boulder County (search) sheriff's Lt. Phil West said.

"The thing I find so troubling is even when confronted with a situation like this, by her own admission, she decided to end somebody's life instead of calling for help," West said. Investigators were trying to determine if the man indeed tried to kill himself, he said.

Inconsistencies in the girl's story and their initial investigation — including the absence of a suicide note — led them to arrest the teenager.

West said the girl was unemotional when investigators arrived at the house Sunday.

"Especially with what (investigators) encountered, they thought her demeanor was not keeping with the circumstances and that raised their suspicions as well," West said.

She and her father lived together; her mother lives elsewhere in the Boulder area. Deputies arrested the girl that afternoon after interviewing her with her mother present. No names were released.

An autopsy found the cause of the man's death was multiple gunshot wounds.

Boulder County Deputy District Attorney Pete Maguire (search) said prosecutors are not sure whether they will charge the girl as an adult or a juvenile.