LVMPD would not confirm the information about the threatening note.
"Due to the open status of the investigation, the content of the note will not be disclosed at this time", police said in a statement Monday.
Heller next to the door to his office when they responded to a call from a burglar-alarm company just after 9 a.m. Sunday morning.
Officers took a report for the letter and are investigating the incident, they said.More news: Singer R. Kelly accused of holding women in 'cult'
The Las Vegas office of U.S. Senator Republican Dean Heller burglarized Sunday.
A spokesperson for the senator declined to comment, saying the office "can't comment on or discuss ongoing investigations". Ever since Trump administration announced efforts to repeal and replace Obamacare, pressure on the senator has been mounting to show his support for the bill.
Heller has attracted attention within his party in recent weeks for expressing his concerns over the GOP's Senate health care proposal. Neither the Vegas police nor Heller's office has confirmed their reporting as of yet.