For example, they skipped over the location of the most-explosive chemicals in the compound, one employee said.

WSJ: Algeria Probes Possible Role of Local Workers in Attacks

They are trained to detect up to a dozen different explosive compounds, including PETN, the compound that AbdulMutallab is alleged to have smuggled aboard Northwest flight 253 to Detroit on December 25.

CNN: Are dogs the key to bomb detection at airports?