On April 1, Jiwon Lee, a 29-year-old dental student at Columbia University and a stand-up comedian, made two phone calls—one to her brother and one to an unknown number—and left her Upper West Side apartment. She hasn't been seen or heard from since.

The second phone call, which lasted 30 minutes, was to a California number that her friends and family didn't recognize. According to Gothamist, the number was disconnected sometime Wednesday, less than one day after Lee went missing.

Citing unnamed NYPD sources, the New York Daily News reports that Lee suffered from depression and attempted suicide several days before she went missing. Lee also left notes in her apartment claiming that she was "sorry she did not live up to expectations," and that she "could not live anymore," according to the Daily News. Similar reports from the Daily Mail were denied by an NYPD spokesman on Sunday.

Prior to enrolling at Columbia, Lee was a popular figure in New York City's stand-up comedy world. From Brooklyn Vegan:

Jiwon was a familiar face on the comedy scene for years. There was a time when I saw her name appear on so many upcoming comedy calendars it was ridiculous.

Lee, who was in her fourth year at Columbia and just weeks from graduating, also worked as an Americorps volunteer.

Lee's brother, Matt, set up a GoFundMe page to crowdsource money to hire a private investigator.

"The NYPD has been amazing, but understandably have many responsibilities to attend to," he wrote. "We would like to pursue hiring a private detective at this time in order to expedite and prioritize the search process. Any funds not used for the private detective will be used as a reward for information leading to her finding."