Former police commissioner Khoo Boon Hui was in Qatar for a work trip when he received a text message claiming that his son, an officer with the Singapore Civil Defence Force, was injured in the Little India riot while his son's friend was killed.
This turned out to be false, and Mr Khoo, who is currently the Senior Deputy Secretary of the Home Affairs Ministry, quickly replied to prevent the rumour from spreading.
He told the Committee of Inquiry looking into the Dec 8 riot yesterday: "I quickly checked, and said: 'No, no, please stop this. It's not true. No one was killed'."
He highlighted this to illustrate how easy - and how dangerous - images and rumours could go viral in the age of technology.
"If you look at this message, there's so much credibility, you know, (it says that) my son was injured and his friend was killed," Mr Khoo, who was police chief from 1997 to 2010, said. "That means it's quoting a very primary source."
The potential "spillover" effects of such rumours mean there could be "wider ramifications" for the police in quelling public order incidents.
If unfounded rumours - such as police taking excessive action against the rioters - spread, they could heighten tensions and inflame violence in other areas, added Mr Khoo.
He said: "In this day and age, it's even worse because you can WhatsApp, SMS with photos, and there's no context. Someone sees something, (they) react."