Shirley Duguay & Douglas Beamish [Purr-fect Match] Forensic Files Case

Human DNA is an important and common way of identifying individuals in any case. However, it was the first time an examination of cat hair DNA was used to solve a criminal case.

Summary of Purr-fect Match Case of Forensic Files

Summary of Purr-fect Match Case of Forensic Files
  • Year of incident: 1994
  • Place: Prince Edward Island, Canada
  • Victim: Shirley Duguay (32 years)
  • Accused: Doug Beamish (Shirley’s husband)

On 7th October 1994, police received a call from a woman about an abandoned car near her house. Police went there and discovered the car at a crime scene.

The car had no license plates and medium velocity blood spatter inside the windshield. But there was nobody.

The car was registered to a local woman, Shirley Ann Duguay, who was missing for the last four days.

Police deduce one of the largest searches that last for 28 weeks. In meantime, they recovered a shovel, a pair of sneakers, and a man-sized jacket that possibly doesn’t fit Shirley as she is less than 5 feet tall.

Lastly, her body was recovered near the river bank of Canada’s Enmore river.

Forensic analysis: White brittle hairs were obtained from the leather jacket. After examination, it was found that the hairs were of the cat named Snowball which belonged to Shirley’s husband Douglas Leo Beamish.

After DNA testing of the hair sample, it was proven that the hair belong to the cat Snowball and was linked to Doug Beamish as accused. He was arrested and charged with murder and sentenced to 18 years in prison.

Forensic Evidence Against Doug Beamish

CarAbandoned in field Missing license plate, medium-impact blood spatter inside of the windshield and side windows
Pillow Found nearby crime scene Soaked in blood and found to be Shirley’s from DNA testing
ShovelAbout a half mile away from Shirley’s carTwo long black hairs of Shirley
Plastic bag15 miles away from Shirley’s carFound a pair of sneakers and a blood-stained leather jacket 
Sneakers In plastic bag Shoe was size 9
Leather Jacket In plastic bag The bloodstained jacket was of a man’s size and too large for Shirley
White Brittle hairInside the jacket Thicker medulla (>0.50) confirmed animal hair
Shirley’s bodyCanada’s Enmore riverbank A shallow grave resembles a pile of brush

Forensic Analysis of Evidence in the Purr-fact Cat Case

Forensic Analysis of Evidence in the Purr-fact Cat Case of Douglas Beamish

A. Hair from Shovel

  • Instrumentation: Microscope
  • Sample: A shovel with two long black hairs attached.

Hairs were compared with hair taken from Shirley’s hair brush. The forensic expert concluded that both hair samples were microscopically identical.

This confirmed that the hair on the shovel might belong to Shirley.

B. Hair from Leather Jacket

  • Instrumentation: Microscope
  • Sample: Around 20 brittle white hairs were found inside of the leather jacket.
  • Human hair vs Animal hair: Medullary index of animal hair is generally more than 0.5 while human has less than 0.33.
human hair vs hair of cat animals

Under a microscope, the hair has thick medullas— a clear indication of animal hair. Now, the next question arises which animal do they belong to?

Coincidently, constable Roger Savoie remembered that Doug has a pure white cat, Snowball. The hair from Doug Beamish’s cat ‘Snowball’ matched microscopically with that on a leather jacket.

Read More: Michael Prozumenshikov & Zachary Persitz [Going for Broke] Forensic Files Case Study

C. DNA Testing from Bloodstains

Bloodstained found in the case:

  • Windshield inside the Car: matched with Shirley by DNA comparison with her father, Melvin Duguay.
  • Pillow nearby the Car: Matched with Shirley by DNA testing.
  • Leather Jacket: Matched with Shirley through DNA testing.

D. Pressure Points in Sneakers

  • Analysis type: Footprint casting
  • Sample: A pair of sneakers of size 9 (same size as Beamish’s)

Analysis of sneakers was done by Dr. Keith Bettles, and based on three facts, he concluded that sneakers were worn by Mr. Beamish.

Casting: Beamish’s feet were cast with Styrofoam molds and then poured with Plaster of Paris. Mold was set to dry which was later compared to the pattern in a pair of shoes.

Fact 1: Everyone wears shoes Differently

The development of individualistic characteristics is mainly because of the variation in size, shape, and mechanics of walking. This creates a pressure and depressed part over the sole.

Moreover, each finger toches the sole with different pressure points which are unique to each person.

Comparison: Using computer software, the casted footprints were pressed against the sole result is developing similar pressure points as that of Mr. Beamish’s.

Fact 2: Mr. Beamish’s toes were Hyperflexed

When a finger (in cases toes) was stretched more creating a pattern over the front of the shoe majorly by the chafing nails and rubbing at the inner lining of the sole.

Fact 3: Beamish’s feet were Pronated

Douglas Beamish's toes were pronated

Pronated feet mean inward or outward flex of the leg with the ground. In the case of Beamish, they were inward.

Dr. Keith Bettles cut the top housing of the sneaker for the examination of hyperflexion and pronation signs. He concluded that there were chafing toes marks as well as patterns caused by pronated feet.

How did Doug’s cat Snowball become Crucial Evidence?

How did Doug's cat Snowball become Crucial Evidence

The killing of Shirley Duguay was the first case that was solved using a cat’s DNA.

Samples: 20 white brittle hairs were recovered from the leather jacket.

Theory: Constable Roger Savoie identified the hair could be from Doug Beamishe’s cat Snowball. So, the investigator’s goal was to prove that hair belong to Snowball which ultimately linked jackets to Doug Beamish.

Procedure: Investigators took help from Dr. Stephen O’Brien, a geneticist at the National Cancer Institute in the United States who had been studying hereditary illness in cats for decades.

After collecting blood samples from Snowball it was sent to Dr. O’Brien. One of the hair samples contained roots.

Dr. O’Brien cut the root pieces from the hair and put them into a buffer solution which dissolved everything except DNA. It was then amplified or photocopied.

The DNA profile of the hair found in the jacket was then compared with the DNA profile recovered from Snowball’s blood.

Result: The genotype of each of the markers matched.

Conclusion: So, Dr. O’Brien concluded his report that the hair samples most probably came from the cat Snowball.

Note: In hair, nuclear DNA is only present in the roots. Mitochondria DNA can be extracted from other parts of hair such as the cortex and cuticle.

Read More: Graham and Margaret Backhouse, Colyn Bedale-Taylor: The Blood Trail Forensic Files Case Study

Is DNA for Cats as Unique as Humans?

Yes, DNA for cats is as unique as humans. To prove the theory. Dr. O’Brien took the blood samples from 20 random cats on Prince Edward Island.

The DNA profile of those 20 cats showed a rich genetic diversity. With the use of the product rule of approximation, the chance of getting the same DNA profile in two cats would be one in 70 million.

This proved a theory that cats’ DNA is as unique as human’s.

Similarly, other animals’ DNA is also as unique as humans’ because of the random nature of parentage and the randomness of the recombination of genes from each parent.

Convection and Punishment for Doug Beamish

Doug Beamish was proven guilty of killing Shirley Ann Duguay. He was charged with second-degree murder and sentenced to 18 years in prison in 1996.

In the year 2022, he was still behind bars because as per the Parole board, he is not ready for “full parole.”

Shirley’s sister Arsenault adds in the parole hearing,

“I am asking — if the offender is released — he not be allowed to live in the Prince County area of Prince Edward Island,”

Shirley’s sister Arsenault words

So, still Douglas Beamish is in prison.


  • P.E.I. man who killed wife in 1994 granted a 12-hour escorted absence from prison [CBC]
  • Muderpedia [link]
  • Forensic Files – Season 7, Episode 7 – Purr-fect Match [YouTube]

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