As the first funerals and amemorial service brought tens of thousands of mourners to Littleton, the suburban community outside Denver where 12 pupils and a teacher were shot dead at Columbine High School last week, police and judicial authorities wavered drastically in their public statements.
A few days ago, investigators were increasingly sure that Eric Harris and Dylan Klebold, the two teenage gunmen who allegedly turned their guns on themselves after shooting their classmates, must have had help, if only to transport more than 30 explosive devices, including a propane bomb intended to blow up the cafeteria.
On Saturday, however, John Stone, Jefferson County sheriff, said they had found a diary belonging to one of the two gunmen indicating they had been planning the attack for up to a year. The diary detailed good places to hide, times of day when the cafeteria was at its fullest, hand signals the gunmen should use, and a countdown to "rock and roll time".
The diary did not appear to mention accomplices, and yesterday officials shifted their line from "when" they find further suspects to "if".
On Friday, Jim Parr, spokesman for Jefferson County, had said the investigation was putting together a profile of a third gunman. But statements at the weekend suggested this assumed that a gunman in a white T-shirt was someone other than Harris or Klebold.
At least one student has said that Harris was wearing a white T-shirt under his trench coat. "Maybe we're back to two suspects instead of the white-shirt third suspect," Steve Davis, sheriff's spokesman, said.
Mr Davis at first lent credence to a "death manifesto" supposedly written by Harris the day before the shootings in which he blamed teachers and parents for driving him to violence and threatening further bloodshed by 26 April - today. Within hours, however, Mr Davis backtracked, saying the message appeared to have been written after the shootings.
The investigation into the shootings is the biggest and most complex in Colorado's history, involving about 150 agents from local law enforcement bodies to the FBI and the Bureau of Alcohol, Tobacco and Firearms. More than 2,000 pieces of evidence have been collected from the school, and hundreds of interviews conducted - with different agents, in the confusion, sometimes interviewing the same person two or three times by mistake.
No arrests have been made. Three or four young people were taken into custody immediately after the attack. At least two of them had nothing to do with the school. They were released shortly afterwards.