by Kathryn Joanne Dixon

Susan Polk was arrested for stabbing to death her husband of twenty years Dr Felix Polk in October 2002.  Approximately seven months later she provided the police with a knife she said she used to kill her husband.  It was a paring knife she said she placed in a kitchen drawer at the home where she and her husband and children lived in Orinda.  After initially denying involvement in the crime, Susan told detectives that she and Dr. Polk argued.  He pulled a paring knife on her and got on top of her on the floor of the pool room cottage of their family estate. Susan kicked him in the groin, took the knife from him and stabbed him in self defense.  She said he suddenly stood up and exclaimed he was dying, then fell backward on the floor.  Her forensic pathology expert Dr. John Cooper opined on May 4, 2006 that Dr. Felix Polk died of coronary insufficiency caused by atherosclerosis and not from loss of blood from the knife wounds.  Dr. Cooper’s testimony directly contradicts that of Dr. Brian Peterson, the Contra Costa County medical examiner, who contends in effect that Dr. Polk bled to death from the multiple stab wounds.

What knife stabbed Felix Polk?  And why does it matter?

It is essential to the defense of Susan Polk.  She elicited testimony about other potentially relevant knives, even though she said she produced the weapon used in the killing.

During the testimony of Eli Polk on May 3, 2006, Susan Polk, on re-direct examination, elicited testimony from her son which identified five knifes which he obtained from storage.  Eli testified he knew these to be knives from the Orinda home.  These knives were submitted as evidence in boxes and were impossible for spectators to observe completely.  Eli described them variously as two knives from a kitchen silver knife set, one a bread knife, and another a knife that was broken off at the tip, and yet another knife which was not broken off.  Finally he identified a cleaver still stuck in its large wooden holder.  Eli explained that Budd McKenzie, lawyer for the Polk estate, had stored these knives.  The implication was that the Orinda police did not seize all knives on the premises as part of their securing the murder scene and investigating the death of Dr. Felix Polk.

Lisa Sweetingham of Court TV reported on March 29, 2006 that the police did seize at least one possible knife used as the murder weapon:

The videotape came in through the testimony of Detective Costa, who took the stand and testified that he also seized Polk's computer, which contained diaries that Polk intends to share with jurors when she begins her case, and a wood-handled kitchen knife from the dishwasher that was tinged with "red dried stuff."

Prosecutors claim criminologists have examined several knives from the Polk residence, but they have been unable to positively identify which, if any, inflicted the multiple stab wounds found all over Felix Polk's body.

The prosecution’s DNA test on the “red dried stuff” did not reveal if the DNA was Dr. Polk’s or Susan's.  Animal blood could also not be ruled out as its source.

Contra Costa County’s medical examiner Dr. Brian L Peterson identified twenty-seven stab wounds.  He did not specify the exact type of knife which in his expert opinion caused these wounds nor did he designate the dimensions of any such knife.  He simply stated it was a “single blade” knife.

The two paring knives submitted as evidence.  They do not have without hilts.  Their exact dimensions have not been provided by any experts.  The typical Wusthof paring knife is 3 to 3 ½ inches long, and possibly 4” long, with no hilt and no guard.  Its width at the end nearest the handle is estimated by this reporter to be 1 to 1 ½ inches. 
(Source: )

At the trial, Deputy District Attorney introduced into evidence a 4 1/2 inch paring knife with a black handle and no hilt.  At trial Susan Polk testified that this knife was the paring knife she used to kill her husband.  She said she took if from the pool house after the murder, and cleaned it and put in back into a kitchen drawer where it was usually stored.  Click.  She provided this knife to the police approximately seven months after her husband's death.  It's exact dimensions were never introduced at trial, although it was described as 4 1/2 inches long.

Are the stab wounds in the autopsy findings by Dr. Peterson consistent with their being caused by a 4/ 1/2 inch single blade paring knife?

Dr. Peterson states the cause of Dr. Polk’s death was “Multiple (27) stab, incised and blunt force injuries of the head, torso and extremities. (Click. Report of autopsy, 11,9,02, first page)

Under the heading “anatomic diagnosis”, Dr. Peterson states, in part, “A.  5 stab wounds extending into chest and abdomen (A, D, J, K, X)… D.  All stab injuries consistent with single edge blade.”

The autopsy by Dr. Brian Peterson further describes these 5 stab wounds, in addition to the other various lesser wounds caused by the knife such as “stab injuries”, “superficial stab wounds”, “scratches” and “incised” wounds.

These five stab wounds are described in the autopsy report as:

"A.  11 1/2 inches below the vertex and 1 3/4 inches to the right of the midline is an irregular 2 X 3/4 inch stab wound.  The sharp margin is lateral, blunt margin is medial and the wound overall is "s" shaped, just below the right clavicle.  Internally, a hemorrhagic wound track extends front to back at approximately 30 degrees and downward into the right upper lung lobe.  On the pleura, the stab injury measures 1 1/4 inches in length, also showing a single sharp and single blunt margin.  The approximate measurement from skin surface to wound termination in lung was 5 1/2 inches.  Associated conditions include a right hemothorax, approximately 100-ml of liquid and clotted blood, as well as diffuse hemorrhage in the right upper lung lube."

D.  21 inches below the vertex and 2 inches to the right of the midline is a ¾ X ¼ inch stab wound oriented from 3 o’clock to 9 o’clock with the blunt margin medial.  This stab intersects laterally with a 1 7/8 inch scratch (oriented from 10 o’clock to 4 o’clock) with an additional ½ inch downward extension.  An additional non-connecting 1 ¾ inch scratch is inferior to this wound.  Internally, a hemorrhagic wound extends through the soft tissue of the chest wall to enter the anterolateral pericardial sac.  The heart itself is not injured.  The approximate length of the injury from skin surface to pericardium is 1 ½ inches in a direction that is right to left and upward.

J.  22 ½ inches below the vertex and 2 ½ inches to the left of the midline is a stab wound oriented from 1 o’clock to 7 o’clock with the blunt margin superior, the short margin inferior.  This stab measures 1 X ¼ inches. It is associated with a lateral scratch measuring 9 inches in length.  Just medial and inferior to this stab is a 6 inch superficial incised wound beginning just left of the midline, extending downward and to the right with 2 additional downward extensions measuring 1 inch each.  Internally, wound J extends through the abdominal wall, through the anterior wall of the stomach, and into the stomach.  The posterior wall of the stomach is uninjured, but due to the nature of the stomach, the length of this wound cannot be determined.

K.  20 inches below the vertex and in the left posterior axillary line is a 1 inch gaping to 1/2 inch stab wound with protruding fat. The blunt margin is anterior, the sharp is posterior.  Internally a hemorrhagic wound extends through the chest wall and through the left hemidiaphragm in a direction that is back to front, left to right, and downward.  The stab defect in the diaphragm measures 1 inch in length. The wound overall measures approximately 3 inches in length.

X.  22 ½ inches below the vertex, beginning 3 inches to the right of the midline is a 4 X ½ inch stab wound (lateral) with an extending incised wound (medial).  Following 2 inches of uninjured skin, a continuing scratch extending upward and to the left measures 1 ½ inches in length.  Associated with the scratch is an intersecting 2 ¾ X ½ inch purple contusion forming overall an “X” shaped pattern. Internally a hemorrhagic wound extends into the right perinephric fat, but does not injure the kidney itself.  The trajectory is right to left, back to front and downward, and the wound measures overall approximately 5 inches.

Dr. Peterson opines in the autopsy report that the knife used was single edged.  He does not state the length of the knife.  Nor does he identify its greatest width at the top of the knife where the handle would begin or where a hilt would be found.

Why doesn’t the Contra Costa County District Attorney set forth to the jury the nature of the stab wounds and introduce expert opinion as to the type of knife or knives involved?

Stab wound “A” and stab wound “X” may have been caused by 5 inch long knives, and the remaining stab wounds "D", "J" and "K" are consistent with 3 inch long knives, such as a paring knife, and with gaping entry wounds consistent with a paring knife.

Specifically, the wounds consistent with a paring knife include the following: 

Stab wound “D” was a gaping entry wound measuring ¾ X ¼ inches and was 1 ½ inches deep. 

Stab wound “J” had a gaping entry wound 1 X ¼ inches and the depth of wound incapable of measurement given entry into the stomach.

Stab wound “K” had a 1 X 1/2 inch gaping entry wound and was 3 inches deep.

The stab wounds consistent with a 5 inch knife, 2 inches wide at the place where the handle or hilt would begin are wounds “A” and “X”

Stab wound "A".

Stab wound “A” is 2 X ¾ at the place where the knife entered the skin.  Therefore the knife wound at the surface of the skin was wider than that the largest width of a paring knife which is about 1 to 1 ½ inches wide.  The thickness of the blade of a paring knife is less than ¾ inches. A possible explanation of the larger dimension of wound “A” as compared to a paring knife’s, could be that a cutting motion would be needed to make a 2 X ¾ inch gaping wound where the knife entered.

Dr. Peterson states regarding stab wound “A”: “The approximate measurement from skin surface to wound termination in lung is 5 1/2 inches.”

Thus, stab wound “A” is 2 to 2 ½ inches longer than the stab wound a paring knife would cause.  Is there any explanation?  A surgical type of powerful straight in and straight out thrust could be required to enable a paring knife to make a 5 ½ inch wound.  Compressibility of tissue could be a factor in enabling a paring knife to make such a wound

A very strong person is more likely to making cutting motions and powerful stabs than a weak person.

Susan Polk was a 110 pound weakling and her husband was larger and stronger at 175 pounds, 5’ 9” tall.  Although Dr. Polk was age 70, by all accounts he was physically fit.

Was stab wound “A” caused by a paring knife or was it caused by a large 5 inch blade knife, 2 inches wide at the hilt?  No expert testimony has been adduced so far at trial to unravel this mystery.  Stab wound “A” was aimed at the right lung and caused a right hemothorax, approximately 100-ml of liquid and clotted blood, as well as diffuse hemorrhage in the right upper lung lube.

Stab wound "X".

Stab wound “X” is 4 X ½ inches at the place where the knife entered the skin.  A paring knife entry wound would be approximately 1 to ½ inches wide and up to approximately 3/4 inches thick.  Dr. Peterson stated: “The trajectory is right to left, back to front and downward, and the wound measures overall approximately 5 inches.”  This description raises the direct inference that a 5 inch long knife, not a 4/1/2 inch long paring knife was used to inflict Felix Polk's injuries.  Stab wound "X" was aimed at the kidney and almost reached it.  It caused internal hemorrhage.

The autopsy results are consistent with a theory that two knives were in involved in the death of Dr. Polk, and injured him while he was still alive, thus causing hemorrhage.  One knife is consistent with a paring knife.  The other knife was possibly a big five inch knife, 2 inches wide at the point where blade met the handle.

Why does it matter in the Susan Polk case?

Susan Polk confessed to killing her husband in self defense with a paring knife.  Her confession is somewhat inconsistent with the physical findings regarding the cause of death.

Because of the disparity in the knife wounds and the prosecutions failure to explain that disparity, two jury instructions may move the jury to find reasonable doubt -- instructions 300 and 359.

Instruction 300 requires that neither side is required to call all witnesses who may have information about the case or to produce all physical evidence that might be relevant.  However, willful suppression of evidence by the government constitutes a denial of due process.

Instruction 359 states essentially that a “confession” must be corroborated by a “corpus delicti”, that is, independent evidence of a charged crime.

Copies of these complete jury instructions are set forth below as a footnote.

Finally, the public and the jury have a right to know why the prosecution is not explaining the fact that possibly a five inch long knife, two inches at the hilt, and not a paring knife 4 1/2 inches long, caused two serious wounds to Dr. Polk.

Was Susan Polk skilled at using two knives at a time while engaged in a fight with a person of superior strength?  The question must be asked, did some other person wield a knife during the fight?

Kathryn Joanne Dixon © 5/7/06


The following is a copy of excerpts of California Criminal Jury Instructions published by the Supreme Court of California.


300. All Available Evidence

Neither side is required to call all witnesses who may have information about the case or to produce all physical evidence that might be relevant.

Related Issues:

Willful suppression of evidence by the government constitutes a denial of a fair trial and of due process.  (People v. Noisey (1968) 265 Cal.App.2d 543, 549–550 [71 Cal. Rptr. 339].)  Likewise, willful failure by investigating officers to obtain evidence that would clear a defendant would amount to a denial of due process of law. (Ibid.)  However, failure to look for evidence is different from suppressing known evidence and “the mere fact that investigating officers did not pursue every possible means of investigation of crime does not, standing alone, constitute denial of due process or suppression of evidence.” (Ibid.; see also People v. Tuthill (1947) 31 Cal.2d 92, 97–98 [187 P.2d 16], overruled on other grounds as noted by People v Balderas (1985) 41 Cal.3d 144, 182 [222 Cal.Rptr. 184, 711 P.2d 480] [“[t]here is no compulsion on the prosecution to call any particular witness or to make any particular tests so long as there is fairly presented to the court the material evidence bearing upon the charge for which the defendant is on trial.”].)

359. Corpus Delicti: Independent Evidence of a Charged Crime

The defendant may not be convicted of any crime based on (his/ her) out-of-court statement[s] alone.  Unless you conclude that other evidence shows someone committed the charged crime [or a lesser included offense], you may not rely on any out-of-court statement[s] by the defendant to convict (him/her) [of that crime or lesser offense].  The other evidence may be slight and need only be enough to support a reasonable inference that someone’s criminal conduct caused an injury, loss, or harm.  The other evidence does not have to prove beyond a reasonable doubt that the charged crime actually was committed.

The identity of the person who committed the crime [and the degree of the crime] may be proved by the defendant’s statement[s] alone.

You may not convict the defendant unless the People have proved (his/her) guilt beyond a reasonable doubt.

BENCH NOTES Instructional Duty

The court has a sua sponte duty to instruct on corpus delicti whenever an accused’s extrajudicial statements form part of the prosecution’s evidence. (People v. Howk (1961) 56 Cal2d 687, 707 [16 Cal.Rptr. 370, 365 P.2d 426].)

The corpus delicti cannot be proved by statements made before or after the crime, but can be proved by statements made during the crime. (People v. Carpenter (1997) 15 Cal.4th 312, 394 [63 Cal.Rptr.2d 1, 935 P.2d 708].