Federal investigators planned to visit dozens of shooting ranges and gun stores across Connecticut Sunday, attempting to figure out what led smart but painfully awkward 20-year-old Adam Lanza to murder 26 children and adults at Sandy Hook Elementary School in Newtown, while townspeople and President Obama prepared to attend an interfaith vigil amid sorrow and confusion.

The tragedy brought forth soul-searching and grief around the globe. Families as far away as Puerto Rico began to plan funerals for victims who still had their baby teeth, world leaders extended condolences, and vigils were held around the U.S.

Police said they had found “very good evidence” they hoped would answer questions about the motives of the gunman, described as brilliant but remote, who forced his way into the school in one of the world’s worst mass shootings.

But Lt. Paul Vance of the Connecticut State Police said Sunday that there is no timeline for the motive to be revealed, and authorities still have an “immense” number of witnesses to interview. Vance warned that those posing as the gunman online or on social media — and posting misinformation — will be investigated and prosecuted for possible violations of Connecticut state and federal law.