Hawley Harvey Crippen and Dorothea Helen Puente.

 In 2007 a campaign began to exonerate Hawley Harvey Crippen of the murder of his wife, Cora Crippen, aka Belle Elmore.
John Trestrail, a toxicologist led the research into Dr Crippen, poisoners rarely inflict external damage on their victims. "A poisoner wants the death to appear natural so he can get a death certificate. This is the only case I know of where the victim was dismembered. It doesn't make sense." In my database of 1,100 poisoning cases, this is the only one which involves dismemberment," said Mr Trestrail, who heads the regional poison centre in Grand Rapids, Michigan.

Perhaps John Trestail should have looked at the Dorothea Puente case.

On November 11, 1988, police unearth a corpse buried in the lawn of 59-year-old Dorothea Puente’s home in Sacramento, California. Puente operated a residential home for elderly people, and an investigation led to the discovery of six more bodies buried on her property.
One of the victims found buried in Dorothea Puente's yard was mutilated in order to conceal its identity; its head, hands and lower legs were gone. A forensic worker finally identified the body as that of Betty Palmer, one of Puente's boarders. Her missing parts were never found, despite all of the searches of the house and yard conducted by the police. After Betty Palmer was buried in the backyard, Puente created a fake ID that had her face, but Palmer's name and information on it. She used this to collect Palmer's benefits. Puente was a diagnosed schizophrenic who had already been in trouble with the law. She had previously served prison time for check forgery, as well as drugging and robbing people she met in bars. After her release, she opened a boarding house for elderly people. In 1986, social worker Peggy Nickerson sent 19 clients to Puente’s home. When some of the residents mysteriously disappeared, Nickerson grew suspicious. Puente’s neighbours, who reported the smell of rotting flesh emanating from her vicinity, validated Nickerson’s concern. Although all the buried bodies were found to contain traces of the sedative Flurazepam, the coroner was unable to identify an exact cause of death. Still, during a trial that lasted five months and included 3,100 exhibits, prosecutors were able to prove beyond a reasonable doubt that Puente had murdered her boarders, most likely to collect their Social Security cheques. Though she was formally charged with nine counts of murder and convicted on three, authorities suspected that Puente might have been responsible for as many as 25 deaths. She died on March 27, 2011 at age 82 from natural causes at a California women’s prison facility in Chowchilla.
The question is why would Dorothea poison then mutilate the bodies? Crippen and Puente have two things in common, slightness of build, and a desire to capitalise on the deaths of their subject/subjects.
Both killers feared the victim overwhelming them in their fight for life. Dorothea persisted cashing her victims' cheques and Hawley continued using his wife's jewels to finance his lifestyle – after all, he was her next of kin. What was hers, was his.