Credit: Chelsea Lauren/Getty Stringer

It’s no mystery: A.J. Buckley of CSI: NY is expecting a baby with fiancée Abigail Ochse. The new dad can barely keep his excitement to himself, tweeting earlier today, “Good morning. Big announcement today. So excited to share #lifechanging.”

The news was officially confirmed by A.J.’s rep to People later in the day; Abigail, an oncology nurse, is reportedly five months along, the rep told the magazine before adding, “The couple look forward to welcoming their new addition in early 2014.”

And should we be picking up pink or blue crime scene tape for the nursery?

“I'm having a baby girl!!! Happiest day of my life #daddyslittlegirl,” AJ tweeted along with an ultrasound photo of the little one.

Credit: A.J. Buckley on Twitter

“Thank you for all the kind wishes! So excited to be a dad,” he later added.

A.J. played lab tech Adam Ross on the show, which was canceled earlier this year after nine seasons on CBS. Since then, A.J. has been busy producing and starring in the independent film North of Hell alongside Katherine Heigl and Patrick Wilson.

Congratulations to the happy couple! We can hardly wait to see what Gary Sinise brings to the shower.

Sources: People and A.J. Buckley on Twitter