A self-described celebrity stalker kept trying to contact Ivanka Trump and her relatives even as he faced charges of harassing her and a court order to stay away, prosecutors have said.
Justin Massler pleaded not guilty to upgraded charges.
The Nevada-based Massler - who had his name legally changed to Cloud Starchaser and gave his address as "a volcano in Hawaii", prosecutors said - is being held without bail.
Massler, 28, was initially arrested last year. New York prosecutors say he unleashed a slate of emails and tweets about his fixation with the NBC Celebrity Apprentice co-host, whose parents are Donald and Ivana Trump.
In tweets directed at Ivanka Trump, Massler said his "dream in life" was to marry her, according to the court complaint.
At times, his remarks turned more bizarre and ominous, the document said.
He threatened to commit suicide in her Manhattan jewellery store and said he wanted to "talk some sense into" her husband, Jared Kushner, and "commandeer" the newspaper that Mr Kushner publishes, The New York Observer.
Massler also has said he would die before being caught and "would go down in a hail of gunfire," assistant district attorney Lucrece Francois told a judge.
Massler's lawyer, George Vomvolakis, has said the messages did not amount to crimes. Massler, who has spent time in a mental hospital, never came close to Trump and did not intend to follow through on his comments, the lawyer said.