Clark Baldwin, The Serial Killing Trucker

On Wednesday May 6, 2020, investigators arrived at Clark Perry Baldwin's home in Waterloo, Iowa, and placed him under arrest for multiple murders. Brent Cooper, the district attorney general of the 22nd Judicial District in Tennessee announced the arrest later that day, revealing that Baldwin was the main suspect in three cold cases, one in Spring Hill Tennessee, and two in Wyoming. Baldwin is suspected of the 1991 murder of Pamela Rose Aldridge McCall and her unborn baby, and the 1992 murders of Bitter Creek Betty and the I-90 Jane Doe and her unborn baby. He was charged in Tennessee with two counts of murder in the case of McCall and her unborn baby. Two murder charges were also brought against him in Wyoming for the murder of the two Jane Does, Bitter Creek Betty and the I-90 Jane Doe, who had been discovered 400 miles apart in 1992. Baldwin, who grew up in Nashua, Iowa, graduated from Nashua-Plainfield High School in 1979. As an adult, he was a resident of a few different towns, including Nashua, Missouri, Waterloo, Virginia, Newport News, and Springfield. He worked as a long-haul trucker for Marten Transport for a number of years, spanning the times and locations of the murders.
Baldwin's arrest came as a surprise to friends and neighbors, many of whom described him as a quiet person, with one person going as far as stating that he was a "gentle giant."
What possessed Baldwin to commit the atrocities he did?