In one entry, Krim says that after dropping her two older children at school she cherished the "3 precious hours with little" Leo.
The nanny, Yoselyn Ortega, was found near a knife with stab wounds to her neck. She was hospitalized in critical condition.
Police Commissioner Raymond Kelly said it was unclear how long the nanny had worked for the family. No charges have been filed.
The children's father, CNBC digital media executive Kevin Krim, who had been away on a business trip, was met by police at the airport on his return and was given an escort to the hospital where his loved ones had gathered.
The couple's apartment building sits in one of the city's most idyllic neighborhoods, a block from Central Park, near the Museum of Natural History and blocks from Lincoln Center for the Performing Arts. The neighborhood is home to many affluent families, and seeing children accompanied by nannies is an everyday part of life there, making the idea of such violence even more disturbing to residents.
Police Commissioner Raymond Kelly said it was unclear how long the nanny had worked for the family and the police investigation was ongoing. No charges have been filed.
Starr, the neighbor, said she believed the nanny had been hired just recently.
"I met her in the elevator, the day before yesterday, and was making small talk," she said.
After police arrived, she said, the mother remained in the building's lobby, screaming hysterically and clutching her surviving child.
Her blog, called Life with the Little Krim Kids, portrays a devoted mother who adores her children, and is charmed by their daily observations and latest tricks. It is filled with family pictures and the children happily posing together.
In a February entry, Krim writes about visiting their nanny's family in the Dominican Republic. She refers to the woman as Josie; it's not clear if it's the same nanny found wounded Thursday.
"We met Josie's amazing familia!!! And the Dominican Republic is a wonderful country!!," she wrote.
In an entry from May, she describes Leo's obsession with his new Crocs.
"Even at nap time — Josie, our nanny, took them off and he screamed bloody murder, so she put them back on and he went right to sleep," she wrote.
The family had moved to New York from San Francisco within the last few years. The children's father was named general manager of CNBC's digital media division in March, after working previously in digital media at Bloomberg. Their mother also had a cooking blog and taught art classes to young children.
The family lived in a stately, late 19th-century apartment building where one three-bedroom unit currently available for rent has an asking price of $10,000 per month. They had a greyhound, retired from racing, named Babar.