Ronnie grew up in Bensonhurst, where he was close with the Falconeri family, especially Olivia Falconeri and her son Dante Falconeri. He and Dante both became police officers, and with Ronnie going into the field first, he later became Dante's lieutenant. Ronnie had been on the Zacchara case since 2007. He got Dante into the undercover unit to infiltrate the Zaccharas.
In 2009, Ronnie and Dante went to Port Charles undercover to infiltrate the Zacchara crime family and the Corinthos-Morgan crime family and bring them down from the inside. Little did they know that Dante was actually Sonny Corinthos' eldest son, Sonny being the head of the Corinthos-Morgan crime family. As Ronnie and Dante started to infiltrate the Corinthos organization, he noticed that Dante was getting close to Sonny and kept a watchful eye over him to make sure that he stayed with the mission. He warned Dante not to get too close and worried that Sonny and Dante's new-found closeness could cause Dante to cross the line between them and the mob.
In early 2010, it was revealed that Ronnie had a past with the crazed and dangerous artist Franco. Before he was accepted into the police academy, he allowed Franco to take the fall for a crime that he himself had committed. He later repaid Franco by releasing him as a suspect on another case, not knowing Franco was becoming a serial killer. Due to their past association, Franco ran Ronnie over with a car to expose him and he ended up in General Hospital. While in the hospital, he is questioned and threatened by an angry Jason Morgan, who wanted information on Franco's whereabouts because Franco had abducted his girlfriend Sam McCall.
In late January, after Dante is exposed as an undercover cop, Sonny shoots him point blank in the chest and his mother Olivia comes running in screaming and reveals to Sonny that Dante is his son. Ronnie then angrily arrests Sonny for the murder of Claudia Zacchara and warned him to stay away from Dante. With their evidence in place, Ronnie prepares to take Sonny down, but is disappointed when Dante tells the police that Sonny did not shoot him, but when he was snooping through one of Sonny's desk drawers, he found a gun, and upon trying to take out the clip, he accidentally shot himself. This statement lost him his job with the NYPD, but Dante later went to work for the PCPD and Ronnie joined him there, becoming his partner. Overtime, as Dante began to work more and more with Sonny and Jason during certain situations, like the search for Franco for example, Ronnie started to look at the association with disdain, and reminds Dante to stick with the mission of taking them both down. He never forgave Sonny for shooting Dante and his desire to take him down became so great that he even showed signs of corruption himself, by stealing and hiding Johnny Zacchara's gun after he was shot by Sonny in self-defense. He wanted to bring Sonny down so badly that he was even willing to frame him.
In the summer of 2010, Ronnie was also involved in trying to send Jason back to prison, after he had been released into Dante's custody to look for the fugitive Franco. As time went on, Ronnie began to distance himself from Dante because he did not approve of his tactics and felt that he had forgotten all about their original mission of taking Corinthos down. In the summer of 2011, when a crazed Lisa Niles puts General Hospital on lockdown, Ronnie adamantly objects to Dante and police commissioner Mac Scorpio's decision to work side by side with the mob by letting Jason inside of the hospital to help diffuse the hostage situation. Ronnie continues to be determined to take Jason, and especially Sonny Corinthos, down.
In late 2011, several of Abby Haver's friends start getting attacked for being dancers. The case goes on for months and the PCPD come up with few leads. Officer Delores Padilla and Michael Corinthos become especially interested in the case, Delores because her sister had been killed in similar circumstances and Michael because he is determined to stop this guy and help Abby's friends after her tragic death. Michael pressure his brother Dante and the PCPD to come up with a suspect. Ronnie, Dante, Delores, and Lulu, who had just gotten a job as the PCPD's evidence room file clerk continue to work the case. Dante, Ronnie and Lulu start to suspect Delores' husband Eddie Cabrera in the attacks and eventually bring him in for questioning, however after witnessing a moment between Delores and Eddie, Lulu starts to realize that Eddie couldn't have done it and he was framed.
Lulu's new hunch leads her right to the identity of the real attacker, none other than Ronnie himself. When Ronnie learns that Lulu is on to him, he kidnaps her and takes her to a motel. A pregnant Sam Morgan is also staying at that same motel and when she hears Lulu struggling in the room, Ronnie kidnaps her too. He takes Lulu and Sam to the abandoned Haunted Star and ties them up. After trying to talk Ronnie down, Dante and John McBain arrive on the scene. Sam manages to untie herself and then Lulu. Shots are fired and Lulu and Dante get out of there while McBain deals with Ronnie. Ronnie grabs Sam in a standoff with McBain and points the gun at her stomach, however Sam faints and when she falls to the ground and Ronnie is shot and killed by John seconds later.
Allowed Franco to take the blame for stealing money from a liquor store prior to entering the police academy [pre-2009; revealed on Jan 14, 2010]
Covered up Franco's murder of Joey Limbo [Dec 2009]
Framed Dante for the attacks on the dancers at Vaughn's and made it look like he was a dirty cop [Apr 30-May 7, 2012; Dante was arrested on Apr 30, 2012 and released by Delores Padilla on May 3, 2012; the charges against Dante were dropped on May 7, 2012]
Kidnapped a very pregnant Sam Morgan and then held her and Lulu hostage at The Haunted Star [May 4-7, 2012]
Admitted he had attacked several dancers [May 2012]
Threatened to kill Dante, Lulu, Sam and her unborn baby [May 7, 2012]
Held Dante at gunpoint [May 7, 2012]
Grazed Lulu in the arm with a bullet [May 7, 2012]
Fired several gunshots at Det. John McBain [May 7, 2012]
Held Sam hostage at gunpoint and threatened to kill her and her unborn baby [May 7, 2012]