One police officer is accidentally shot by another during a raid gone wrong. Dr. Sloan investigates the victim's wife, the shooter, and a conniving lawyer when he suspects foul play.
A burglar inadvertently becomes infected with a deadly virus. Dr. Sloan and Jesse are subsequently exposed to the virus after Jesse stumbles upon the thief's dead body. Both Mark and Jesse are confined to Mark's home while Steve and Amanda investigate the drug company that manufactured the virus, in the hopes of discovering an antidote before Jesse runs out of time.
A figure skater hires her ex-coach to attack a rival skater. Dr. Sloan tries to prove her guilt.
Mark, Steve, et al, investigate a string of the so-called ""Casanova"" murders. Dr. Sloan loses his detached perspective when the killer begins calling Mark.
Dr. Sloan investigates a photographer, the overly protective mother of Jesse's friend's fiancée, in the murder of a private investigator.
A respected cardiologist murders an innocent man in an insurance scam. Dr. Sloan reluctantly investigates his friend.
A young undercover detective investigates a militia-type organization to solve a terrorist bombing witnessed by Mark. She has to decide whether to risk blowing her cover and warn Dr. Sloan of an attempt on his life or finish her assignment.
A bus accident brings multiple victims into the hospital. Amanda does the bulk of the investigating when its discovered that a casualty in the accident was actually murdered.
His scheming advisor covers up the accidental death of the drug-addicted daughter of a U.S. Senator. Dr. Sloan and Amanda investigate.
An ADA sets out on a vendetta against an Asian youth, against both Mark and Steve's advice, after a drive-by shooting at a high school leaves one teacher dead.
Mark's daughter returns after eight years, leaving an abusive husband who later turns up dead.
When a famous prostitute writes a tell-all book, an executive's job at Community General is in serious jeopardy.
Mark investigates a 30-year old murder when the body of his old mentor is discovered entombed in a wall in the hospital.
Jesse is arrested and charged with murder after a doctor testifying against Jesse in a malpractice suit is poisoned. Mark convinces his old friend, Ben Matlock, to defend Jesse.
Amanda and Ben investigate the murder of Eric Spindler while Jesse continues to languish in jail.
Mark aids an old friend, Joe Mannix, in solving a 25-year-old, unsolved murder.
When a musician is found murdered at a Country Music Awards ceremony, Dr. Sloan and company rush to find the culprit before the show ends and the crowd disappears.
A devious psychologist uses hypnotism to facilitate his criminal acts, including the murder of his wife.
An aggressive female pharmaceuticals representative stalks the hospital's new chief of staff after a one-night-stand, hoping to break up his marriage and have him all for herself.
A beach boy involved with a gang member's sister is suspected of murdering him. Mark investigates.
Dr. Sloan investigates when an unpopular colleague drops dead while performing an operation. Mark investigates his fellow doctors when tests reveal the deceased was poisoned.
Dr. Sloan and Amanda investigate when the co-pilot of the airplance carrying them to a medical conference is murdered and the remainder of the flight crew are incapacitated with a mysterious illness.
A wealthy woman and her boyfriend dupe Mark and plot to murder her husband.
A bungling comedian seeks revenge on his former partner when he's cheated out of millions.
Dr. Sloan is stalked by a mad bomber whom he helped incarcerate. Norman and Mark are the main dissenters in negotiations to sell the hospital to a corporate raider.
Watch Diagnosis: Murder Season 4, Episode 25: Comedy is Murder online on FlixGems. A bungling comedian seeks revenge on his former partner when he's cheated out of millions.