The husband and wife responsible for last week’s mass shooting in California were discussing ‘jihad and martyrdom’ together as early as 2013, FBI Director James Comey said Wednesday.

Comey unveiled the information while he was speaking to the Senate Judiciary Committee.

Investigators have been working to determine the circumstances that led the husband-and-wife team of Syed Rizwan Farook and Tashfeen Malik to open fire during a holiday party for Farook’s coworkers, killing 14 people and injuring 21 others exactly one week ago.

President Barack Obama has called the shooting an act of terrorism, and investigators had said the suspects were radicalized for “quite some time,” though Comey’s revelation to the lawmakers provided the most specific account yet of how and when the suspects became radicalized.

Comey said the FBI’s investigation “indicates that they were actually radicalized before they started courting or dating each other online,” dispelling notions that one suspect radicalized the other. By the end of 2013, Comey said the two “were talking to each other about jihad and martyrdom” online before their engagement, marriage and Malik’s move to the United States.

Yet none of these conversations apparently triggered any red flags, as Comey had previously told reporters that neither Farook nor Malik was on the FBI’s radar screen at the time of the attack.

Farook, a United States citizen, was born to Pakistani parents in Illinois. He met Malik, a Pakistan native who was living in Saudi Arabia, on an online dating website. Malik originally came to the United States under a “fiancee visa” waiver program that has been highly scrutinized since the attack, with federal lawmakers and Obama calling for reviews to the program. The fact that Malik was apparently radicalized before she came to America could spur further scrutiny.

While authorities have not linked Farook or Malik to being part of a larger terrorist group, investigators are trying to uncover what initially led the suspects to become radicalized and whether they were inspired by the work any foreign terrorist groups.

Police have said they recovered at least 4,500 rounds of ammunition and 19 pipes that could have been used to produce bombs from the couple’s home in Redlands, California.

Farook and Malik died in a shootout with police, leaving behind a 6-month-old daughter.