Pakistani police say they have arrested a teenage boy who has confessed to being part of a team instructed to kill opposition leader Benazir Bhutto.
Pakistan accuses militia leader Baitullah Mehsud of being behind the killing
It was the first arrest in connection with last month's assassination.
Security officials say the boy told them he was part of a backup squad trained to attack, if the initial attempt on her life had failed.
But local newspapers say investigators are treating the boy's claims with caution.
The unnamed 15-year-old was arrested in Pakistan's North West Frontier Province along with a more senior militant, officials say.
He allegedly told investigators that he would have been "next in line" to attack Ms Bhutto.
He also named a local militia commander, Baitullah Mehsud, as being behind the assassination, officials say.
Mr Mehsud has already been accused by the Pakistani authorities but denies any involvement.
The director of the US Central Intelligence Agency has also implicated Mr Mehsud in the assassination.
Pakistan's Interior Secretary, Kamal Shah, said interrogators were trying to get supporting testimony from the second detainee before accepting the teenager's confession.