The quest to find out who murdered A.J. Quartermaine (Sean Kanan) has launched a full scale investigation in Port Charles, and the noose is slowly tightening around Sonny (Maurice Bernard) and Ava's (Maura West) necks on General Hospital.

Authorities Begin To Close In On Ava and Sonny?

At Michael's (Chad Duell) insistence that someone pay for shooting and killing his biological father, Anna (Finola Hughes) and Dante (Dominic Zamprogna) have launched a full-scale investigation to determine what happened, and who shot the ultimately fatal bullets.

"We might be about to find out who killed A.J.," Anna says to Dante in a preview clip for the Tuesday, April 15 episode.

Michael Struggles With Who KIlled A.J.?

As the investigation unfolds, Carlos (Jeffrey Vincent Parise) finds himself coming under suspicion when his interest in the case sparks Michael's curiosity.

"You seem pretty interested in this," Michael says to him.

Carlos, who secretly works for both Julian (Michael DeVry) and Ava (Maura West), was hired by Ava to kill A.J. before, but failed; and he knows everything -- not only that Sonny (Maurice Bernard) killed A.J., but that Ava killed Connie. He may be trying to ensure he doesn't become a suspect so he doesn't go to jail for crimes he didn't commit. However, when his behaviors make the police and Michael suspicious, he could throw both Ava and Sonny into jail by spilling the truth.

If Carlos doesn't turn them in, Duke (Ian Buchanan) could. He will interrupt Sonny at home while he has an all-too-revealing mental breakdown from the stress of keeping his secret and sees A.J.'s ghost -- who torments him.

"Get out of here!" Sonny screams at A.J.'s ghost.

"I beg your pardon?" Duke asks.

General Hospital airs Monday-Friday at 2 p.m. on ABC.