Michael Swango was valedictorian of his 1972 Quincy Catholic Boys High School class. During high school he played clarinet in the band.

Swango served in the Marine Corps, graduating from recruit training at Marine Corps Recruit Depot, San Diego; he received an honorable discharge in 1976. He saw no action overseas during his Service, but his training in the Marines left him with a commitment to physical exercise; when not studying, he was frequently seen jogging or performing calisthenics on the Quincy campus, and he was known to perform pushups as a form of self-punishment when criticized by instructors. Swango attended Quincy University, graduating summa cum laude and being awarded the American Chemical Society Award. Following his graduation from Quincy, Swango went to medical school at Southern Illinois University School of Medicine.

Despite a very poor evaluation in his dean's letter from SIU, Swango got a surgical internship at Ohio State University Medical Center (now The Ohio State University Wexner Medical Center) in 1983, to be followed by a residency in neurosurgery. While he worked in Rhodes Hall at OSU, Nurses noticed that apparently healthy patients began dying mysteriously with alarming frequency. Each time, Swango had been the floor intern. One nurse caught him injecting some "medicine" into a patient who later became strangely ill. The Nurses reported their concerns to administrators, but were met with accusations of paranoia. Swango was cleared by a cursory investigation in 1984. However, his work had been so slovenly that OSU pulled its residency offer after his internship ended in June.

In July 1984, Swango returned to Quincy and began working as an emergency medical technician with the Adams County Ambulance Corps even though he had been fired from another ambulance Service for making a heart patient drive to the hospital. Soon, many of the paramedics on staff began noticing that whenever Swango prepared the coffee or brought any food in, several of them usually became violently ill, with no apparent cause. In October of that year, Swango was arrested by the Quincy Police Department, who found arsenic and other poisons in his possession. On August 23, 1985, Swango was convicted of aggravated battery for poisoning co-workers. He was sentenced to five years' imprisonment.

In 1989, Swango, now released from prison, found work as a counselor at the state career development center in Newport News, Virginia. He was forced out after being caught working on a scrapbook of disasters on work time. He then found a job as a laboratory technician for ATICoal in Newport News, now Vanguard Energy, a division of CITA Logistics. During his time there, several employees sought medical attention with complaints of persistent and increasing stomach pains. Around this time, he met Kristin Kinney, a nurse at Riverside Hospital. The two fell in love and planned to marry once they got settled. He was employed until 1991, when he resigned his position to seek out a new position as a Doctor.

In 1991, Swango legally changed his name to Daniel J. Adams and tried to apply for a residency program at Ohio Valley Medical Center in Wheeling, West Virginia. In July 1992, he began working at Sanford USD Medical Center in Sioux Falls, South Dakota. In both cases, he forged several legal documents that he used to reestablish himself as a physician and respected member of society. He forged a fact sheet from the Illinois Department of Corrections that falsified his Criminal record, stating that he had been convicted of a misdemeanor for getting into a fistfight with a co-worker and received six months in prison, rather than the five years for felony poisoning that he served. Most states will not grant a medical license to a violent felon, considering a violent felony conviction to be evidence of unprofessional conduct. He forged a "Restoration of Civil Rights" letter from Virginia Governor Gerald L. Baliles, falsely stating that Baliles had decided to restore Swango's right to vote and serve on a jury, based on "reports from friends and colleagues" that Swango had committed no further crimes after his "misdemeanor" and was leading an "exemplary lifestyle".

The government used this time to amass a dossier of Swango's crimes. As part of that investigation, prosecutors exhumed the bodies of three patients and found poisonous chemicals in them. They also found evidence that Swango paralyzed patient Baron Harris with an injection of what was supposedly a sedative. The sedative caused him to lapse into a coma, and Harris died on November 9, 1993. Additionally, prosecutors found evidence that Swango lied about the death of Cynthia Ann McGee, a patient he treated during his internship at OSU. Swango claimed she suffered heart failure; he had killed her by giving her a potassium injection that stopped her heart. On July 11, 2000, less than a week before he was due to be released from prison on the fraud charge, federal prosecutors on Long Island filed a Criminal complaint charging Swango with three counts of murder, one count of assault and one count each of false statements, mail fraud and conspiracy to commit wire fraud. At the same time, Zimbabwean authorities charged him with poisoning seven patients, five of whom died.

By that time, Swango had fled the country. In November 1994, he went to Zimbabwe and used forged documents to obtain a job at Mnene Lutheran Mission Hospital in the center of the country. Again, his patients began dying mysteriously. As a result of suspicions of the medical Director there, Dr. Zishiri, Swango was suspended. Because of the failure to perform adequate autopsies, no firm conclusions could be drawn. During his suspension, he hired prominent Lawyer David Coltart to enable him to return to clinical practice. He also appealed to the authorities at Mpilo Hospital, Bulawayo, to allow him in the interim to continue working voluntarily there. However, this was opposed by Dr. Abdollah Mesbah, a surgical resident, who had often found him snooping around mysteriously on the wards and in ICU even when not on call. He had suspected that sudden deaths of some patients were due to Swango, but had no proof at that stage.

While all this was happening, Veterans Affairs Office of the Inspector General Criminal Investigator Tom Valery consulted with Charlene Thomesen, M.D., a forensic Psychiatrist. Because of her considerable clinical expertise, Thomesen was able to review documents and evidence and give a psychological profile of Swango, along with her assessment of why he had committed such crimes. Valery was called by the FBI to discuss holding Swango; Valery called then Drug Enforcement Administration (DEA) Basic Agent Richard Thomesen, who was stationed in the Manhattan DEA Office, to discuss the case. Thomesen's conversation focused on Swango lying on his government application to work at the Department of Veterans Affairs, where he prescribed narcotic medications. There was enough evidence for Immigration and Naturalization Service agents to arrest Swango in June 1997 on a layover at Chicago-O'Hare International Airport on his way to Saudi Arabia.

Faced with hard evidence of his fraudulent activities and the possibility of an extended inquiry into his time in Zimbabwe, Swango pleaded guilty to defrauding the government in March 1998. In July 1998, he was sentenced to 3.5 years in prison. The sentencing judge ordered that Swango not be allowed to prepare or deliver food, or have any involvement in preparing or distributing drugs.

Swango was formally indicted on July 17, 2000 and pleaded not guilty. On September 6, he pleaded guilty to murder and fraud charges before Judge Jacob Mishler. Had he not done so, he faced the possibility of the death penalty in New York and extradition to Zimbabwe. At his sentencing hearing, prosecutors read lurid passages from Swango's notebook, describing the joy he felt during his crimes. Judge Mishler sentenced Swango to three consecutive life terms; he is incarcerated at ADX Florence near Florence, Colorado.