By the time she made the call, prosecutors say Lowery had already clubbed her boss, Linda Stein, to death with a yoga stick.
Stein was a celebrity real estate broker. Lowery was her personal assistant.
"Just wanted to let you know that I'm leaving work at 5:30. Hopefully the walk in the park was actually good. Um, I left everything off Sid's at the door. And Seymour called, um, and he said, give him a call back because he had something to show you," Lowery said in the voicemail.
Prosecutors allege Lowery's apparent cheery demeanor was all an act as she allegedly attempted to cover her tracks after the murder in Stein's fifth avenue apartment.
Defense attorneys have tried to establish reasonable doubt in the minds of jurors by suggesting others had a motive for killing the sometimes verbally abusive Stein.
Prosecutors also released surveillance video that authorities say shows Lowery calmly leaving the building shortly after her boss' murder.
The tape, along with the voicemail, is evidence of guilt, according to prosecutors.
"And I hope that the showing goes well with Ursula, um, and I will see you tomorrow. So, if you get this before 5:30 you can just call me. If not, talk to you later. Bye," she said on the voicemail.
Prosecutors say that's where the 28-year-old slipped up, telling stein to call before 5:30. Even though authorities say the call was made at 6:00 p.m.
Prosecutors allege Lowery stole from Stein as well. Defense attorneys say their client may have been a thief, but she's not a killer.