Glennon Edward Engleman was born on February 6, 1927, in St. Louis, Missouri, as the youngest of four children. Raised in a middle-class family, his father served in the U.S. Air Force before transitioning to work on the railroad. Engleman was an above-average student but did not excel in any particular subject. After serving in the U.S. Army Air Corps during World War II, he utilized the GI Bill to attend Washington University in St. Louis, graduating with a degree in dentistry in 1954.

Despite his professional facade, Engleman harbored a darker side. He was known to be manipulative, using his charm and financial influence to involve women—ex-wives, lovers, and his dental assistant—in elaborate murder schemes aimed at collecting life insurance payouts. His sociopathic tendencies allowed him to kill without remorse, finding satisfaction in meticulously planning and executing murders for financial gain.

Engleman's murderous activities spanned over two decades, primarily motivated by financial gain through life insurance fraud. His first known victim was James Bullock, the new husband of Engleman's ex-wife, Edna Ruth. On December 17, 1958, Bullock was shot near the Saint Louis Art Museum. Edna collected $64,000 from his life insurance, a portion of which was invested in a drag racing track co-owned by Engleman.

On September 26, 1963, Engleman's business associate, Eric Frey, was killed during the construction of the drag strip. Engleman struck Frey with a rock, pushed him into a well, and detonated dynamite to conceal the crime. Frey's death was initially ruled accidental, and his widow, Sandy, who was romantically involved with Engleman, shared the $25,000 insurance payout with him.

In 1976, Engleman murdered Peter Halm, the husband of his former dental assistant, Carmen Miranda Halm. Engleman had encouraged Carmen to marry Halm, and after his death, she collected $75,000 in life insurance, giving $10,000 to Engleman.

Engleman's most complex scheme involved the Gusewelle family. On November 3, 1977, he killed Arthur and Vernita Gusewelle in their farmhouse near Edwardsville, Illinois. Seventeen months later, on March 31, 1979, he murdered their son, Ronald Gusewelle, in East St. Louis, Illinois. Ronald's wife, Barbara Boyle, with whom Engleman was having an affair, collected approximately $340,000 in life insurance. Boyle was convicted for her husband's murder and sentenced to 50 years in prison, serving just under half of her sentence.

Engleman's final known victim was Sophie Marie Barrera, owner of a dental laboratory to whom he owed over $14,000. On January 14, 1980, Barrera was killed by a car bomb. Engleman was convicted of mail fraud, conspiracy to commit mail fraud, and damaging a vehicle in interstate commerce by means of an explosive, resulting in a 60-year federal prison sentence.

Engleman was arrested on February 24, 1980, and subsequently convicted for multiple murders in both Missouri and Illinois. He received multiple life sentences and died in prison on March 3, 1999, from complications related to diabetes.