By Kristie Macrakis (Guest Contributor)
My favorite secret ink story is about a Nazi spy who secreted invisible ink in his tooth. It’s probably my favorite because one of the most intriguing aspects of the history of secret writing is the inventive way in which people concealed their materials.
A Bizarre Concealment
Of course, hiding invisible ink in a tooth is one of the more bizarre concealments, but it’s a good one because border control agents usually don’t ask people to open their mouths for inspection. Even if they did, there is no reason they should suspect a filled or capped tooth contains invisible ink or poison or other dangerous things spies put in their teeth.
I discovered this story in the security service archives about German World War II secret agents files kept by British National Archives. When I hit the keyword search for secret writing, I came across a number of interesting files, including the one about a Nickolay Hansen. Hansen was a Norwegian coal miner who agreed to work for the Nazis from his home in the coal mining island of Stavanger,Norway, across the sea from Scotland. But the Nazis really wanted him to go to the United Kingdom, parachute out of a plane in Scotland, and find work in a Scottish coal mine, which he could use as a base to transmit military information.
By the fall of 1943, the Nazis’ vision came true. Hansen jumped out of a German plane circling above the Scottish Highlands and parachuted into a field shortly after midnight on 1 October 1943. He wasn’t the first Nazi spy to parachute into England during World War II. After the British forbade Germans and other enemy aliens from entering England, the Nazis snuck their agents onto the island with rubber boats or parachuted them in from the sky. Many of the famous double agents like Eddie Chapman parachuted into the country. The British usually expected these spies because they knew when they were coming by intercepting and decrypting radio communications.
On the night of Hansen’s parachute jump, two Scottish truck drivers taking an overnight shipment of herring to Fraserburgh, Scotland, noticed a plane circling above the woods near the town. When they drove by the field they saw someone waving a flashlight in their direction. They stopped, got out of the cab, jumped over the fence and approached what looked like a German parachute jumper. Hansen quickly confessed. He told them he had one wireless transmitter, but they quickly found a second one. He did not tell them about the invisible ink hidden in his tooth.
Interrogation, Denial, Confession
Like all the other hundreds of caught Nazi spies (many of whom became double agents), Hansen was taken to Camp 020, an interrogation center at Latchmere House in South London. Interrogators were somewhat bemused by this Norwegian coal miner from the “bowels of the earth.” His German code-name was HEINI, which isn’t exactly flattering – in German it means someone who is somewhat dimwitted. British interrogators also thought he was “dull” but had the clever cunning of a peasant. Even though interrogators asked Hansen if he had secret writing materials and a cover address where he was instructed to send messages, he denied it until several weeks of interrogation and an unfortunate incident.
Hansen finally confessed that he had learned the fine art of secret writing at the Akershus Fortress in Oslo by a rather small and fat German with fair thinning hair named Dr. Gordon. Gordon taught him how to rub the paper with cotton wool before writing and how to create his own invisible ink matches (the Heinrich method) impregnated with quinine.
When it came time to stash Hansen’s invisible ink, a German operative proceeded to fasten a tiny rubber bag of invisible ink between Hansen’s toes with glue that he then covered with grease paint. But Hansen needed to take a bath and removed the small bag from his toes. Thereafter, the Germans thought of hiding it in his hair or under his armpit, but instead decided to pay a visit to a dentist in order to secret the baggie in a tooth.
An Unusual Dental Appointment
When Hansen visited the dentist in his hometown of Stavanger, the dentist opened up one molar, placed a small bag of invisible ink in it and then sealed it with cement. He then started work on the tooth next to it; this time he didn’t seal the cavity but rather placed the small baggie in it and covered it with dental putty because it was not possible to cement it shut. Instead, he gave Hansen a small celluloid cap to place on that tooth when eating. Hansen lost the cap the same evening while slightly drunk.
Hansen had completely forgotten about the second filling until he was having lunch at Camp 020. He suddenly had a strange taste in his mouth. He spat out what he was eating and found the small rubber bag with invisible ink and threw it out the window. Although he saved some of the secret ink substance from the food, British investigators didn’t find it. As a result, a camp officer who was also a dentist opened up the other tooth and extracted the material.
The Secrets of Secret Ink
I should note that the subject of secret ink is so hidden that even though these files have been released, the description of the substance is deleted in the copy at the archives. Luckily, I had access to some American OSS files and was able to determine that the substance was, in fact, quinine.
Even though the British interrogators found this damning substance, Hansen still refused to reveal the cover address he was to send his secret messages. After more rigorous interrogation he revealed the Nazi spy address in Sweden. The British concluded that Hansen was to use the secret writing if he could no longer communicate through the wireless sets.
That hiding secret ink in a tooth might be painful is revealed by Hansen’s mugshot above: he looks like he has a toothache.
Kristie Macrakis is an author, historian, and professor whose books include Prisoners, Lovers, and Spies (Yale, 2014), Surviving the Swastika: Scientific Research in Nazi Germany (Oxford, 1993), Science Under Socialism: East Germany in Comparative Perspective (Harvard, 1997), East German Foreign Intelligence (Routledge, 2010) and Seduced by Secrets: Inside the Stasi’s Spy-Tech World (Cambridge, 2008) (Translated into German, Czech and Slovak and a History Book Club Selection). This article previously appeared in March 2014 at her blog.