He is aware of the Stargate program's existence and also possess full security clearance. When Teal'c was stung by an Infestation fly on Svoriin, the insect venom began to transform Teal'c's DNA. When Dr. Janet Fraiser was out of her league, Timothy Harlow was brought in to help, as he was considered one of the world's top geneticists and he already had full security clearance. He worked with Carter at The Pentagon before she joined the Stargate program.
He discovered that Teal'cs genetic code was being rewritten as a result of the alien bug and he would eventually be transformed into one of the bugs. Later, after working on the problem, he believed he needed a sample of the insect's venom, which prompted SG-1 to fetch some from Svoriin. He studied the body of the insect SG-1 recovered. After extracting the venom, he was able to create an anti-venom, which would slow the transformation process and, coupled with a Goa'uld symbiote, would be able to reverse the process. Feeling guilty about informing the NID about Teal'c's condition, he destroyed all the samples of the alien bug in order to stop them learning anymore about it. (SG1: "Bane")