Nothing seemed amiss with the nanny or the children, she said.
Later, Friedman was back in the elevator -- heading out to run errands -- when she heard a "primal scream" from somewhere in the building.
"It was pure terror," she said. "...It was unlike anything I've ever heard before."
She isn't sure who she heard scream. But after she got off the elevator, Friedman saw the youngsters' mother screaming on the mezzanine.
News of the crime spread quickly. Some parents in the neighborhood said they rushed home to hug their own children.
Maryellen Conway, 39, a mother of two, said she called her children's nanny and they cried together. "She was in tears. I trust her, obviously, with my life and she's part of our family," Conway said. "There's no words to describe what they're going through."
On Friday morning, Jasmarin Rothbarb was pushing a stroller near the Krims' apartment building. She said she employs a nanny, but the killings have made her question whether to continue.
"It's a tough call," she said. "You trust these people with your most precious joys. I think I see more mothers out today than nannies. It's a horrible thing."
Outside the building, Kathleen Peters placed flowers at a makeshift memorial. Peters, a mother herself, also works as a nanny for children who live a few blocks away. "It makes me really, really sad," she said. "I can't understand why (the nanny) would do something like that."
The apartment is a block west of Central Park and four blocks south of the American Museum of Natural History, two locations popular with nannies.
It is not unusual for their employers to treat nannies as extended members of their own families. That was the case with the Krims. Marina Krim's blog, "Life with the Little Krim Kids," offered the loving mother's view of a family life that included Ortega as a member.
Last February, the Krims traveled to the Dominican Republic, where they met their nanny's family.
"We spent the past nine days in the Dominican Republic," Marina Krim wrote on February 18. "We spent half the time at our nanny, Josie's sisters home in Santiago and the rest at Balcones de Atlantico in Las Terrenas, a condo-style hotel where the 'Real Housewives of Dominican Republic' and their families hang on weekends. It was wonderful."
She added, "We met Josie's amazing familia!!! And the Dominican Republic is a wonderful country!!"
One photograph showed the families together, the nanny holding the girl who was learning how to swim at the time her siblings were killed.
The blog included hundreds of photographs and notes about picking blackberries, celebrating birthdays, going to a pumpkin patch.
On September 30, Marina Krim posted a photograph of her son after his second birthday. The boy had a mischievous look as he played at a toy kitchen set. "Leo 'Lito' Krim!!!!! Yes, the 2 year old boy," his mother wrote. "One of the best parts of my day is after I drop both girls off at school and have 3 precious hours with little Lito all to myself. Ok, I'm near getting cheesy I adore this boy so much!!!"
Weeks before his birthday, mom and son walked home, with the lad pointing at toy cars, trucks and fire engines, excited in anticipation of his birthday. "Mama, present, present," he said after spotting a toy helicopter.
"Lito, I must say, is a very clever little boy," she wrote. "He is super talkative and just has a million thoughts running through his brain and can express himself amazingly well for an almost-2 year old."
In April, 6-year-old Lucia, known as Lulu, accompanied her father on a take-your-child-to-work event. On the whiteboard in her father's office, she wrote: "I like your ofis Dada. Love LuLu."
Marina Krim logged her final entry at about 2:30 p.m. Thursday, three hours before the killings were discovered.
"Leo speaks in the most adorable way possible. Firstly, he speaks super clearly, so you can understand every word (he) is saying. And he does things like, 'I want a fresh bagel' and 'Dito (what he calls himself) wants cold milk' and most adorable of all, 'No thank you' -- he never uses 'No' alone, it's always paired with 'thank you.'"
Within hours of the killings, hundreds of people had left messages of condolences on the blog; by Friday morning, it had been taken down.