The militants used Google to check Mr Martinkus's claim that he was working for Australian public broadcaster SBS.
"They had thought he was working for the Americans as an informer," said Mike Carey, executive producer at SBS.
"In this case, modern technology probably saved the journalist's life."
Mr Martinkus, who had been captured at gunpoint outside the al-Hamra hotel in Baghdad, was eventually released on Sunday.
More news from dotJournalism:
Online publisher dares US government contractor
Another Iraq combat video surfaces
Baghdad training project forced to close
Plea to help solve Iraqi 'torture' riddle
See also:
Silicon.com coverage: http://networks.silicon.com/webwatch/0,39024667,39125122,00.htm
SBS: http://www.sbs.com.au
Free daily newsletter
If you like our news and feature articles, you can sign up to receive our free daily (Mon-Fri) email newsletter (mobile friendly).
Related articles
- Revenue and tech: Five must-read news reports for your newsroom
- Media analyst Thomas Baekdal: 'News publishers must stop fighting for the scraps of ad revenue'
- Post-Perugia thoughts: what went wrong between big tech and the news?
- Audiences, AI and audio apps: five talking points from Perugia
- Protecting independent journalism, with Lexie Kirkconnell-Kawana of IMPRESS
