A CUNY professor admitted to becoming obsessed with a grad student working in his department in the latest black eye for the public university that saw a teacher threaten a Post reporter with a machete last month.

The creepy Kingsborough Community College math professor sent sexually inappropriate texts and emails to the grad student, even saying her message sign-off got him aroused, according to court filings.

Ayalur Krishnan, a 52-year-old tenured associate professor, was slapped with a one-semester suspension for the inappropriate messages he sent to the grad student, who The Post is not identifying.

In a 2020 email he sent her, he blamed his behavior on “compulsions.”

He included the letter in the suit he filed Tuesday in Brooklyn Supreme Court disputing his suspension.

Krishnan argued in court that the arbitrator who determined his punishment mischaracterized some of his messages and took others out of context.

The grad student, who was 21 when she was hired as an administrative coordinator in 2017, told the school she had a professional relationship with Krishnan for two years before things began to change in late February 2020.

She told investigators that the professor had become increasingly “obsessed” with her and would “constantly” — sometimes up to 20 times a day — send her texts and emails, often with “unwanted” sexual tones.

In one email, he told the student that her new email sign-off, which included only her name, caused him to have a “priapism,” which is a long-lasting, painful erection.

Krishnan, who was paid $105,833 last year by CUNY, is slated to return in August.

He joins a long list of CUNY professors accused of crimes or misbehavior that have observers ripping the taxpayer-funded school system for its poor vetting of employees.