The doctor murdered by a deranged former physician was remembered Saturday as the polar opposite of the madman who took her life — a selfless caregiver who treated “all patients as VIPs.”

Dr. Tracy Sin-Yee Tam, 32, was covering a shift for a colleague Friday when she encountered Henry Bello on the 17th floor of Bronx-Lebanon Hospital Center on Friday. He opened fire, fatally shooting her in the neck, and then committed suicide with a shot to the chest as police closed in.

“She was the closest human being to an angel I have ever met,” said a friend.

Tam graduated Touro College medical school in 2013 and received her medical license that same year, records show.

Like Bello, she was a family-medicine doctor but usually worked in the hospital’s satellite clinic, rarely taking shifts at the hospital, friends and co-workers said.

It was not clear if Bello even knew Tam, who had only worked at Bronx-Lebanon for about a year and who was supposed to be off duty when Bello burst in. She had agreed to pick up the extra shift Friday, hospital officials said.

“She was very well liked by hospital staff, and we are certainly grieved throughout the hospital,” said Bronx-Lebanon spokesman Errol Schneer, who said Tam worked at the Mount Hope hospital for a year. “It’s a very tragic event for us as well.”

Tam’s tight-knit family, including her father, a cab driver; and mom, a homemaker who recently started working again, returned to their family’s Hillcrest, Queens, home on Friday to find detectives waiting for them, a neighbor said.

“The mother came home first. As soon as she went inside, I heard screaming. I know it was her,” Mahmudur Rahman, 58, recalled on Saturday. “The dad came around 8, 8:30 p.m. I heard him scream out, too. I know they are hurting right now.”

Tam and her younger sister grew up with Rahman’s kids.

“They shovel the snow together, they clean the cars, go shopping. They are the model family,” he said.

Neighbors were stunned.

“It’s a crazy-person world out there,” said Pat Vicencio, 55, who lives down the street. “I cried when I heard. Why it had to be her? Why?

“She was a very nice girl — shy and friendly. She always said hello when she passed by,” Vicencio said.

Neighbor Alena Khaim, 23, saw the family leaving with detectives.

“They looked distraught . . . It was the saddest thing ever. I knew something horrible had happened. It’s really sad. It makes you think anything can happen to anybody. She was such a sweet girl.”

Additional reporting by Ariel Ramerez