 A witness who was to testify Thursday in the federal trial of three men accused of plotting to rob an armored car was excused for the day after admitting smoking marijuana several hours before.

During questioning with the jury out of the room, Chad Davis told U.S. District Judge Leon Holmes that he had smoked a joint around 6 a.m. Thursday. That was less than five hours before Davis was to testify on the fourth day of trial for Antonio Person, former Little Rock police officer Jason Gilbert and former U.S. Department of Veterans Affairs officer Allen Clark.

"I'm not trying to be funny," Assistant U.S. Attorney Michael Gordon asked Davis at one point, "but how big was the joint?"

Davis replied that it was about the size of a cigarette and that he had smoked half of it.

Holmes ruled minutes later, saying he believed Davis was likely coherent to testify but that it didn't make sense to take the chance in a trial that will likely continue through the end of next week. He ordered Davis to return first thing Friday morning.

"Do not use marijuana between now and then," Holmes told him. "Or anything else."

Davis reportedly was working at a bus station near the site of a 2007 armored car robbery. Prosecutors contend that Person carried out that robbery and that Clark and Gilbert were in on the conspiracy to plan it.