Accused transgender killer Nikki Secondino gave cops a chilling confession to Thursday’s slashing attack on her dad and sister — declaring that she “wanted them dead” and boasting that she would have killed others if she could, sources told The Post.

“I came out of the bedroom. My father was sitting on the couch,” she allegedly told cops after the attack inside the family’s Bensonhurst home, which left dad Carlo dead, and sister Liana fighting for her life.

“I hit him on the head with a hammer. Then I reached for my favorite German knife and stabbed the s–t out of him.

“My sister came out and tried to stop me and I stabbed her in the back, head and stomach,” Nikki allegedly confessed.

“I wanted them dead.

“If I would have seen the 911 caller she would have been next,” she said, apparently referring to a neighbor who called cops.

“I didn’t plan it. I didn’t have to. I don’t remember where I put the knife. I am sure they will find it.”

On Thursday, Nikki, 22, was arraigned on murder and attempted murder charges for allegedly killing her 61-year-old father, and stabbing her 19-year-old siste.

She initially told police that two intruders attacked the family and “sexually assaulted me,” but sources said she later confessed that she concocted the story after the attacks.

Neighbors told The Post they heard Nikki on the phone in the hallway after the attacks claiming the family had been robbed by a pair of home invaders.

Cops arriving at the scene found the elder Secondino lying in a pool of blood on the kitchen floor and his younger daughter conscious but critically injured.

“My sister stabbed me,” the wounded teen allegedly told the officers. “Have you seen my dad? Go get him.”

Nikki Secondino, 22.
Nikki Secondino, 22, is charged with murder and attempted murder for allegedly stabbing her dad, Carlo, to death and wounding her younger sister, Liana.
Robert Mecea

The deadly assaults come amid new reports of turmoil in the family.

In late July, Nikki got a temporary order of protection against her dad and sister claiming Liana threatened to kill her and that her father was in “the mob.”

“It was very weird. It wasn’t sophisticated, it was grammatically poor,” one police source said of Nikki’s request for the order.

The family court request came after two tumultuous incidents earlier that month.

On July 15 Nikki called the cops and claimed her father had threatened to kill her, and two days later her sister was charged with assault and criminal mischief for allegedly tearing down window blinds and cutting Nikki’s hand.

A judge agreed to sign off on the order, said sources, who added that her father, Carlo, was not believed to be connected to the Mafia.

Carlo and Liana Secondino.
Carlo Secondino was stabbed to death and his daughter. Liana, was wounded.
Facebook/Carlo Secondino

On Friday, a page was created for Liana and her father, with the site raising more than $10,000 by midday.

“Liana is like walking sunshine and brings joy and positivity with her wherever she goes,” the page says. “Liana’s father, Carolo, loved her so much and worked hard every day to be the best father he could.

“Right now Liana needs our support due to tragic events, so please give if you are able.”

Nikki Secondino, 22.
Nikki Secondino, a transgender woman, is charged with murder in her father’s death and attempted murder for allegedly wounding her kid sister.
Instagram/Nikki Secondino

Police said Nikki was treated for slash wounds to her hands.

Her father worked as a deliveryman at a local deli.