TO ASSASSINATE FORMER PRESIDENT TRUMP. WHAT THEY STILL HAVE YET TO FIGURE OUT IS WHY. IN THE WEEKS LEADING UP TO DONALD TRUMP'S RALLY IN BUTLER, PENNSYLVANIA, ON JULY 13th, THE FBI SAYS THOMAS CROOKS WAS SCOURING THE INTERNET FOR INFORMATION ON UPCOMING POLITICAL EVENTS. >> IN THE 30 DAYS PRIOR TO THE ATTACK, THE SUBJECT CONDUCTED MORE THAN 60 SEARCHES RELATED TO PRESIDENT BIDEN AND FORMER PRESIDENT TRUMP. >> Reporter: CROOKS WAS SEARCHING FOR INFORMATION ON BOTH THE REPUBLICAN AND DEMOCRATIC NATIONAL CONVENTIONS. HE ALSO SEARCHED FOR DETAILS ON THE TRUMP EVENT, WHICH TOOK PLACE CLOSE TO WHERE HE LIVED. THE FBI DESCRIBES CROOKS' PLANNING AS A, QUOTE, SUSTAINED, DETAILED EFFORT. INITIALLY, CROOKS' SEARCH HISTORY SHOWED HIM LOOKING FOR DETAILS AROUND A WIDE RANGE OF POLITICAL EVENTS, BEFORE ZEROING IN ON THE BUTLER RALLY, WHICH THE FBI BELIEVES CROOKS VIEWED AS A TARGET OF OPPORTUNITY. THEY ALSO BELIEVE HE ACTED ALONE. >> I WANT TO BE CLEAR. WE HAVE NOT SEEN ANY INDICATION TO SUGGEST CROOKS WAS DIRECTED BY A FOREIGN ENTITY TO CONDUCT THE ATTACK. >> Reporter: BUT THESE DISCOVERIES HAVE NOT PROVIDED MUCH INSIGHT INTO CROOKS' MOTIVE. THE CONTENT ON HIS ACCOUNTS DISPLAYED A, QUOTE, MIXTURE OF IDEOLOGIES. THE INVESTIGATORS ALSO SHARED PHOTOS OF THE COLLAPSIBLE BARREL ON THE GUN CROOKS USED, AS WELL AS THE BACKPACK THEY FOUND ON SITE. THEY ALSO SHOWED THE AC UNIT THAT HE USED TO CLIMB ON THE ROOF. THEY BELIEVE HE SPENT A LITTLE MORE THAN SIX MINUTES ON THE ROOF BEFORE BEING KILLED BY COUNTERSNIPER FIRE. >> RIGHT HERE! HE'S ON THE ROOF! >> Reporter: THE FBI PROBE IS ONE OF MANY INVESTIGATIONS INTO THE ASSASSINATION ATTEMPT. EARLIER THIS WEEK, MEMBERS OF THE BIPARTISAN CONGRESSIONAL TASK FORCE TOURED THE SITE IN PENNSYLVANIA, PROMISING TO GET TO THE BOTTOM OF WHAT WENT WRONG. >> I DEFINITELY TOOK NOTE TODAY THAT THERE WERE A LOT OF LINES OF SIGHT THAT APPEARED TO HAVE BEEN UNSECURED THAT DAY THAT DIDN'T HAVE EYES ON OR THAT WON'T SECURED, AND CERTAINLY, AT THIS POINT, A LOT MORE QUESTIONS THAN ANSWERS. >> THE FBI SAID TO THE ALLEGE'S SHOOTER'S FAMILY IS COOPERATING