One LAPD officer notified the department Tuesday that he was in Washington, D.C. for the events last week.
The officer, whose name is not being made public and whose assignment is not known to NBCLA, said he attended Trump's rally but denied he went to the Capitol.
Earlier Tuesday LAPD Chief Michel Moore said only a "department employee" had self-identified as being in D.C. last week.
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Moore also said any officer who attended the events in D.C. would be ordered to sit for an interview with the FBI to provide information on what he or she witnessed.