NASHVILLE, N.C. — Convicted murderer Michael Peterson has received a minor prison infraction for having too many postage stamps, a state Department of Correction spokesman said.

Stamps are a hot commodity behind bars, according to spokesman Keith Acree, because prisoners use them for trading and bartering.

Indigent inmates used to receive, all at once, 10 stamps a month, but because too many inmates were using them for other purposes, the policy was changed. Now, inmates get one stamp about every three days.

A former Durham newspaper columnist and novelist, Peterson was declared indigent in October 2003 after he was convicted of first-degree murder in connection with the death of his wife, Kathleen Peterson. She was found dead at the bottom of a staircase inside the couple's Durham mansion in December 2001.

Peterson is still at the Nash Correctional Institution, where he is serving a life sentence and awaiting a decision from the North Carolina Court of Appeals on his murder conviction.

At one point, the one-time millionaire earned $1 a day teaching GED classes to other inmates. Acree said that Peterson lost his teaching assistant position because of the infraction, which is a standard practice, even for a minor problem.

The possession of "no-threat contraband" is Peterson's first infraction since he was admitted into the state's prison system on Oct. 10, 2003. He did spend nearly a month in solitary confinement in early 2004, but prison officials would not ever say exactly why he was placed there.