Preppy Princeton murder suspect Matthew Hertgen posed in creepy pic with cat toy 1 day before allegedly killing brother, family kitty

The preppy Princeton, New Jersey man who allegedly murdered his younger brother and butchered the family feline inside their luxury apartment posed with an $8 cat toy the day before the gruesome killings.

In the creepy pic, Matthew Hertgen, 31, displayed the same thousand-yard stare he had in his mugshot the following day — after cops arrested him for beating and slashing his brother, Joseph Hertgen, to death Saturday night.

Hertgen also posted eerie poems to Facebook during the months before the killing — one of which included verses about “knives sharpening” and “blood oozing out of his eyes.”

Police say Hertgen used a knife and a golf club to kill both his brother and the cat at about 11:15 p.m. Saturday night in Princeton.

Authorities have charged him with murder, and he faces life in prison if convicted.