Last weekend the news agenda was dominated by reports from Syria of more than 100 people being massacred in the town of Houla.
For about 90 minutes on Sunday, the BBC News website illustrated its story about what had happened with a picture of shrouded bodies in neat rows, with a child jumping over one of the rows.
It's an incredibly powerful picture, bringing home the shocking aftermath of a massacre.
Except that it's not from this incident at all, but was taken almost a decade earlier, in Iraq, by professional photographer Marco Di Lauro, who works for Getty Images.
The picture was first spotted as it circulated on Twitter, the social networking site, on Sunday, apparently sourced from activists in Syria, triggering our process for checking user-generated content.
Efforts were made to track down the original source and, having obtained some information pointing to its veracity, the picture was published, with a disclaimer saying it could not be independently verified.
However, on this occasion, the extent of the checks and the consideration of whether to publish should have been better.
It was a mistake - rectified by the removal of the image as soon as it was spotted - and we apologise for it.
Fortunately, such mistakes are very rare. BBC News has a strong track record of using content from non-traditional sources, and of stopping numerous examples of incorrect material making it to air or online - but it does underline the need to handle such material with great care.
Chris Hamilton is social media editor for BBC News. You can find him on Twitter @chrishams