Dr. Rick Decker, the son of a prominent doctor, met Susan Stewart at a medical conference in Florida. A charming man, he quickly gained her affections and followed her to Oakdale. A respected doctor at Memorial Hospital, Susan introduced Rick to her colleagues and soon Rick was offered a job. Not long after his arrival, a number of patients starting dying, patients connected to the hospital's Chief of Staff, Bob Hughes. When it was suspected that the deaths were due to incompetence on Bob's part, Bob stepped down and eventually sought Rick's help in treating his memory lapses. After successfully treating Bob, Rick gained his trust and the trust of others at Memorial. However, the deaths kept occurring. Finally, with the murder of head nurse Krebbs, foul play was suspected and Bob brought in forensic pathologist, Walker Daniels to seek out the truth. At the same time, the Oakdale Police got involved in the case and soon there were two suspects, young intern Dr. Gordon and Rick himself! Though Dr. Daniels thought that Rick fit the profile of a serial killer, Bob refused to consider him as a viable suspect even when he learned that Rick was suspected of murdering patients in San Francisco. Not long after, Bob was attacked and left in a coma for weeks. Soon after, Rick was attacked but recovered quickly. The attack on Rick shifted suspicion on Dr. Gordon who was later found dead, an apparent suicide.

In the midst of this investigation, Rick's staunchest defender was Susan who would not even consider the evidence against him. Soon, Rick convinced Susan to marry him immediately. However, the day of the wedding, he was approached by reporter Jeffrey Starr who was writing a story about his time in San Francisco, more specially the death of several patients there. Realizing he could be caught, Rick murdered the reporter, and then hurriedly married Susan. Desperate to keep his involvement a secret, he drugged Susan that night and then slipped out, made it appear as if Starr left Oakdale, than slipped back in the house without her knowing. However, Rick's troubles compounded when Susan's daughter, Alison, innocently told her mother that she stopped by the house and Rick wasn't there. Though he succeeded in giving Susan a reasonable explanation of why Alison didn't see him, he knew time was running out and threatened Alison to keep her mouth shut or else. Alison wasn't all he had to worry about since by this point the Oakdale PD learned about Rick's suspension in medical school for flatlining--that is, causing his heart to stop. There was also Bob to consider since he could wake up at any time and finger Rick as his attacker. Realizing he was about to be discovered, Rick wove Susan an intricate tale of how he suffered from anxiety attacks and convinced her to go away with him. That was before he realized that Alison had the key to his safety deposit box! Catching her in the act of going through his box, he kidnapped her to a remote location and injected her with what he thought was potassium chloride.

Unbeknownst to Rick, Alison replaced the poison with water. The next day, Susan saw a headline in the paper stating that Alison had been murdered and was last seen in the company of Dr. Rick Decker! Finally acknowledging the truth, Susan angrily confronted Rick who confessed to everything. Though Susan tried to run from him, he caught up with her and held both her and Alison hostage before he was subdued by Chris Hughes. At the police station, Rick confessed to all of the murders and stated that, while he used Susan in the beginning to get a job, he did fall in love with her. Unfortunately, Susan rewarded him with a slap on the face and Rick was sent to await trial for the murders in San Francisco as well as Oakdale.

A year later, at a mental hospital near Oakdale, Rick found himself captivated by Barbara Ryan, a recent resident at the hospital. Although he initially intended to kill her, he changed his mind when he quickly found himself falling in love with her. Barbara seemed to return his affections and plotted with him to escape the hospital so they could be together. Although Rick counted on the help of a janitor who regularly granted him special favors, in exchange for fake prescriptions, the janitor refused to risk his career by participating in an escape. Soon, Barbara came up with another plan-- steal the keys to the hospital from a security guard and then make copies of the keys in a ceramics class. Unfortunately, their behavior drew the suspicion of a security guard and the pair was separated. However, Barbara and Rick found ways to be together, with Barbara continuing to encourage Rick that they'd run away and be together forever. Although oblivious at first, Rick eventually caught on--Barbara was using him. On the night of the great escape, Halloween, Rick confronted Barbara and kidnapped her to the Old Mill and tried to murder her. Unfortunately for Rick, as he was strangling her, Barbara's son, Will, happened by and saved his mother by knocking Rick unconscious.

A few years later, Barbara's son, Paul, was arrested for the murder of a girl named Sofie. Paul's lawyer suggested using a pathologist who had been very successful in investigating matters of foul play. Barbara agreed and was find herself face to face with Rick! Though still imprisoned, Rick was often paid to assist law enforcement officials in investigating suspicious deaths. While conducting his autopsy, while under guard at Memorial, Rick discovered that Sofie could have only been murdered by someone highly proficient in the use of syringes. Though this was a very vital clue, Barbara was far from grateful. At the same time, Rick had run ins with Susan and Alison, neither of whom seemed happy to see him. After Rick was told that his services were no longer needed, he was sent back to jail. After he left, Chris, Alison, Emily and Barbara all received mysterious packages that they assumed were from other people. Suddenly, the group became behaving very erratically. That is except for Barbara. She had lent her gitl—a necklace—to her new daughter-in-law, Meg. After Meg ended up in the psychiatric ward after attempting to murder Paul, Rick called Barbara and practically told her that he was responsible for the poisonings and that he had the antidote. Seeing no choice, Barbara agreed to accept Rick's help in exchange for one million dollars.

At the same time, Police Chief Margo Hughes figured out that Rick was behind the poisonings and confronted him she discovered that he was in Oakdale. Rick denied having done it and told Margo that he could cure all the victims, one being Margo's son, if his sentence was changed to time served. Though reluctant at first, Margo relented and sent Rick to work at Memorial under guard. In the lab, Rick got the upper hand and subdued his guard. Just as he got his handcuffs off, Susan walked in. After declaring his love and kissing a disgusted Susan, Rick injected her with the poison and then ran off. Once outside the hospital, Rick saw all the police surrounding the building. He tried to time his escape, but an officer was able to get the draw on him and told him to freeze. Rick quickly disarmed the cop and looked for a way to get to Paul in the helicopter. He realized his only chance was to go back inside and take a hostage. He grabbed Meg and took her at gunpoint to Alison's room. Suddenly, Margo arrived and there was a standoff. .As Rick and Margo held their guns on each other, Margo's husband, Tom, walked in and seemed to suffer a heart attack when Rick shoved him out of the way. To save her husband's life, Margo let Rick go. For insurance, Rick took an unconscious Alison hostage and made his way to the helicopter that Paul had provided. Unfortunately for Rick, Chris already discovered an antidote to the poison and injected himself with it. As a result, he was able to save Alison and Rick was carted off to prison.