Police in B.C. are investigating a 'baby for sale' ad that someone posted to a Prince George buy-and-sell website.

RCMP Sgt. Steve Perret said a Fort St. John woman was shocked to find that a photo of her baby was used in a fake online "for sale" ad on the Prince George Buy, Sell and Trade site.

Perret said the post, which was removed this week after the investigation began, demonstrated a sick sense of humour and it wasn't the only troubling ad police found.

"To me, this looks like a case of somebody's twisted or perverted sense of humour, by posting these types of ads trying to sell somebody else's child," Perret said.

"Additionally there was an ad where he was trying to sell a dead dog."'

Both Prince George and Fort St. John RCMP are investigating, but won't say if they have identified a suspect.

A baby photo a Fort St. John woman posted to Facebook ended up in a fake 'baby for sale' ad on a Prince George buy-and-sell website. (CBC)

Perret said the fake baby ad could result in mischief charges.

He also said the incident should serve as a reminder to social media users to safeguard their personal information.

Perret said the woman intended to share the baby photo with friends and family by posting it to her Facebook account, but the photo was completely public because she didn't adjust her privacy settings to make photos available for view only to "friends."

"Unfortunately, all too often people put too much information on the internet, which can result in things like identity theft," he said.

"You know, social networking sites like Facebook — they're an excellent means to stay in touch with family and friends, but once you post something on the internet, it's out there forever."

With files from the CBC's Marissa Harvey