Several other airlines, including United and US Airways, have endured delays after reports of suspicious substances.

Florida officials have received more than 100 calls about suspicious substances, none of which turned out to be hazardous.

On October 21, 2012, a line judge saw what he thought was a suspicious substance on hand towels used by the players.

I think we've found a suspicious substance here, young lady,' he said.

Anyway, we leaned on him a bit-seems there were small amounts of suspicious substances in his flat-and he's got a watertight alibi.

They may analyze anything from DNA or fingerprints to human remains or suspicious substances.

An official close the investigation, who insisted on anonymity, said last night that the suspicious substance turned out to be cooking oil.

Are we willing to accept a free-for-all approach to the use of angel dust and other suspicious substances amongst Brazilian beef farmers?

'We wouldn't find any suspicious substances, then, if we turned over your mother's house?'

But, in November, the leading cause of subway delays was still listed as "suspicious substances."