Shipman was convicted in January 2000 and sentenced to life in prison; however, no motivation was ever determined. 

Shipman later died by suicide, in prison, on Jan. 13, 2004. According to the Independent, “Serial killer Harold Shipman timed his suicide so his wife could cash in a £100,000 pension payout, according to secret prison records.” The article continued, “He plotted to end his life before his 60th birthday so he could guarantee Mrs. Shipman a £100,000 lump sum payment and £10,000 a year later from his GP pension. If he died after that point, she would have only been entitled to £5,000 a year.”

Source: https://www.buzzfeed.com/crystalro/serial-killers-countries-around-the-world