Reports that Sandy Hook school shooter Adam Lanza aspired to one-up Norwegian mass killer Anders Breivik are “mere speculation” given the ongoing nature of the investigation, said Connecticut State Police spokesman Lt. Paul Vance.

On Monday night, CBS News attributed to “law enforcement sources” a theory that Lanza saw himself as being in competition with Anders Behring Breivik, the man who killed 77 people in Norway two years ago, many of them teenagers at a summer camp. The story said Lanza wanted to kill even more people and went to the school because it was an easy target.

But Vance said investigators “are a long way” from determining what motivated Lanza. “Determining a motive is a huge undertaking,” he said, “especially given that Lanza is dead.”

Another law enforcement official told NBC News that Lanza had collected material on previous mass shootings. “But there was nothing that outlined his plans or said that he was trying to outdo a previous shooting,” the official said.

Read more at NBC