Former President Donald J. Trump was said to be shocked by what officials described as the second attempt on his life, but sought to reassure friends with humor.
An investigator hired by the global antidoping regulator found no bias toward China in a case that has outraged Olympic athletes and led to an F.B.I. investigation.
The teen suspect was questioned last year about online threats, though nothing conclusive emerged. Many local police departments lack the resources to take deeper looks at suspicious actors.
Some current and former officials have said the 2019 F.B.I. analysis sowed doubt within the C.I.A. and parts of the Trump administration about the root causes of the ailments.