This list covers all minor criminals mentioned in Season Three.
Stanley Howard's unnamed mother
The abusive mother of future serial killer Stanley Howard, she would punish her son by locking him in a closet. Her actions were the catalyst of Howard's later serial killings, and her death in 2006 was presumably the trigger for said killings. How she died or whether or not she was convicted of her actions is unknown.
Mr. and Mrs. Laybourne
A couple that was the first set of murder victims of serial killer Gary. They were killed during a home invasion committed by Gary and his partner and former foster brother Ervin Robles, during which they both noticed they were abusing their daughter regularly. This triggered Gary to commit their murders, since it reminded him of the abuse he suffered at the hands of his foster parents.
Mr. and Mrs. Manwaring
A foster couple (an unnamed woman and her husband Hal) who abused the children under their care using a variety of methods. Mrs. Manwaring committed much of the abuse, while her husband turned a blind eye on it. Among the victims were Gary and Ervin, whose murders were sparked by the abuse. Gary would later try to have their current foster son kill them, but this ploy failed. They were presumably arrested immediately afterwards.
Jessica Davis's killer
Jessica Davis's murder, which predated the episode by one week, was initially thought to be connected to the case at hand. She was abducted from a mall and found dead hours later. According to Reid, the murderer, who remains unidentified and at large by the end of the episode, killed her because he realized that he could never have any privacy with her. News coverage of the murder would later be responsible for launching the prominent case. It seems to have been partially based on the real-life murder of Polly Klaas committed by Richard Allen Davis.
The Scarsdale Skinner
The Scarsdale Skinner (real name unrevealed) was a serial killer operating in Scarsdale, New York. According to Reid, Rossi somehow helped capture him by using psycho-linguistics to profile his reading habits. Judging by the nickname, it can be assumed he flayed his victims.
Henry Frost's unnamed father
The unnamed father of budding serial killer Henry Frost, he threw his son out of the house when he was only 15. Nothing else about him is specified, including if he is alive or dead, or if he was ever prosecuted for his abuse.
(name unrevealed) was a gang member and rapist who appeared in "True Night". He was seen with Glen Hill and the TSK gang when they stumpled upon Vickie Wright, the pregnant fiancée of the psychotic serial-turned-spree killer Jonny McHale. They attacked the couple. He grabbed Vickie and took her to the gang. It is unknown if he was the killer or just raped her.
Jonny McHale killed him and the rest of the gang six months later.
The McCrellan Corporation
A predominantly Irish mob centered in Boston, which Jack Vaughan once worked as an enforcer for. The organization was particularly ruthless in regards to those it viewed as a threat, so any potential witnesses to their crimes never come forward for fear of retribution. The "corporation" may have been disbanded by the testimony of Jack, who had turned against the group and was placed in witness protection after his wife died in an attack that was meant for him. In the Season Twelve episode Green Light, it was revealed that Jack and his daughter Lindsey were eventually let go from witness protection, presumably because the McCrellan Corporation was dismantled for good.
Landon (surname unrevealed) was a traveling circus owner who employed his mentally handicapped son Joe. When the circus passed through Indianapolis in 2007, Joe became fixated on a girl named Connie Galen, following her around the carnival to the point her parents took her home. Joe somehow found her home and, after attempting to find her and accidentally woke her parents, proceeded to brutally murder them with an axe after the father struck him with it. Landon found him and managed to remove almost all of the forensic evidence from the crime scene (except for a single fingerprint, which was useless anyway since Joe wasn't on record). As punishment for the murders, Landon would have the carnival pass through the town around the same time every year. Joe was apprehended by the BAU twenty years later.
It's unknown if Landon was ever prosecuted, since he did help erase forensic evidence at a crime scene (which would constitute obstructing justice, tampering with evidence, or being an accessory to murder).
The Indianapolis rapist
A serial rapist caught by Rossi in 1988. By his account, it was pretty easy as he wasn't very smart. After the case, Rossi was brought in on the murders of Mr. and Mrs. Galen.
The father of serial killer Peter Redding, Charles lived and worked at Brassard college as a professor, where he would frequently molested his son James. Eventually, a 15 year-old Peter killed James to save him from their father's abuse, making his death look like a suicide. Charles' status afterwards is unknown, nor is it known if he was ever convicted of what he did to his son.
The father of spree killer Owen Savage, Lou was a former Marine stationed if Afghanistan when his alcoholic wife, Hope, was killed in a drunk driving accident. Forced to leave and return home because of this, Lou became an alcoholic himself and was also very mentally abusive towards his son. The abuse worsened after Owen was caught on video masturbating and it went viral online. Owen finally snapped and murdered Lou.
The father of Jordan Norris, he also mentally abused and dominated his daughter. Jordan later found a boyfriend in Owen Savage (who was also abused by his widowed father), who would defend her from him and other bullies. Owen finally snapped and murdered both Rod and his own father.