MAN ARRESTED IN 1985 MONTANA DE ORO KILLING
DNA EVIDENCE MAY END 18-YEAR-OLD MYSTERY OF WHO MURDERED MARY CATHERINE WATERBURY;
POLICE ARREST PETER DERKS, 57, MARKING THE FIRST TIME CRIME SCENE DNA HAS LED
TO A SUSPECT IN A SLO COUNTY MURDER
By Nathan Welton
June 3, 2004
of DNA, perhaps collected from a pinhead-sized drop of blood,
led deputies to a suspect this week in an 18-year-old murder case.
Arroyo Grande landscaper Peter Derks, 57, was taken into custody Tuesday on
suspicion of the 1985 murder of former Cal Poly student Mary Catherine Waterbury.
She had been sexually assaulted and strangled in Montana de Oro State Park.
"This is significant because it's the first time we've made a murder case
in San Luis Obispo County based on a DNA match," said county Sheriff-Coroner
Waterbury's slaying had remained unsolved for almost 20 years, but new DNA
analysis helped justify the arrest, deputies said Wednesday. Investigators
also said the department has at least two other unsolved cases to which they're
applying the technology.
Along with two dozen others, Derks had been considered in the case over the
years, but deputies never had enough conclusive evidence to take action.
Waterbury's family could not be reached for comment Wednesday. Hedges said
the recent developments had upset them.
Still, "they were pleased there was potential closure in the case," said
Sheriff's Detective Jay Donovan, who contacted the family Tuesday.
On Oct. 19, 1985, the 23-year-old Waterbury left her San Luis Obispo apartment
to watch the sun set at Montana de Oro State Park.
She was never seen again.
She had been taking time off from Cal Poly to work as a bookkeeper for the
San Luis Record Co. but enjoyed spending her free time in the park.
Her brother, Chris, became worried when she didn't come home to the apartment
she shared with her sister, Julie. He knew she liked the park and went there
to look for her the next day.
He found the car she'd driven, her sister's yellow Volkswagen, abandoned inside
the park off Pecho Valley Road. He then called San Luis Obispo police, who
called search-and-rescue teams.
A storm that night hampered efforts, and officials believed the waters washed
away potentially useful evidence. The rain was so torrential it rendered bloodhounds
Two days after Waterbury disappeared -- and after 100 soggy searchers turned
up nothing -- a helicopter search party spotted the woman's body.
Waterbury's partially clothed, unhidden body was laying in thick brush 300
yards from the car. Crime scene investigators took samples of hair, blood and
An autopsy later revealed she had been sexually assaulted and strangled.
On the trail
At the time, limited forensics technology allowed officials to make only crude
biological comparisons, such as basic blood matching, with the evidence.
"What we could use it for back then was much more primitive than what we
could use it for now," Hedges said. "But we collected evidence,
we preserved evidence, and sometimes science works in your favor."
Officials saved the samples and continued the investigation. Over the years,
leads trickled in, but the case remained stalled.
In 1990, deputies submitted their crime scene samples for genetic testing.
It was then they discovered the evidence had identifiable DNA -- both of Waterbury
and of an unknown other person.
Meanwhile, about two years after the Waterbury murder, Derks was convicted
for assaulting a woman with a deadly weapon.
The crime occurred in the same park deputies say he killed Waterbury.
Derks emerged from prison in 1991. State law enforcement officials took a DNA
sample from him before he left, Hedges said, and added it to a government database
of known criminals for later comparison.
Hedges also said that Derks had a conviction in Texas in the early 1970s that,
had it occurred here, would have mandated his registration as a sex offender.
A new lead
Through the 1990s, no matches returned from Sacramento, and the state's DNA
storage bank remained relatively unused for the next decade, said Nathan Barankin,
spokesman for the state Attorney General's office.
But Attorney General Bill Lockyer took office in 1999 and placed new focus
on emerging DNA technologies, processing a 140,000-sample backlog, Barankin
Upon learning of the new emphasis on DNA testing from Lockyer's office, Hedges
said, local authorities resubmitted crime scene evidence last year.
On May 14, local officials learned of a match between their submission and
His genetic profile is now one of an estimated 210,000 on file.
"We now have thousands of samples in the database," said Department
of Justice Special Agent Steve Utter.
Now, Hedges said, authorities are considering Derks for other unsolved crimes
in the county. They include the suspected 1998 murder of Andrea Hug, whose
body investigators also found in Montana de Oro State Park.
Arrest in Arroyo Grande
Officials apprehended Derks on Tuesday following a two-week surveillance of
his Tally Ho Road home.
Derks' neighbor Ron Kautz said the man was a quiet type who rents an apartment
above the main house, kept up the lawn and did other odd jobs. He lived there
for at least five or six years, the neighbor said.
"He comes and goes quietly," Kautz said. "He was not a nuisance."
Authorities spent a lot of time searching his yard and garage Tuesday, said
Kautz, who lives across the street. Kautz said state agents questioned him
after showing him a picture of an unkempt man to identify. He had never seen
Derks up close and wasn't sure he was his neighbor.
"He was always much better groomed when I saw him," Kautz said. "I
told them, 'I guess it could be the man across the street.'
"I didn't know him by name but I always said 'Good morning' when I'd go
out to get the mail. He nodded, but that was about it."