One of the few times that the identity of the murderer is not revealed until the final scene. Submitted by PaulDrake33, 6/26/2008.
+ Isn’t this actually typical of Perry Mason? Queried by gracep, 1/14/2011.
++ In most episodes, the murderer is revealed in the penultimate scene. The final scene usually takes place in Perry's office where everyone discusses the case, wraps up loose ends, and cracks a joke or two. Submitted by PaulDrake33, 1/26/2011.

Although his appearance is brief, Uncle Martin (Wellman) as played by Alexander Campbell is one of the most despicable characters ever on Perry Mason in my opinion. Often in the Perry Mason series, the viewer finds himself conflicted over the resolution of the case. The viewer wants the (presumed innocent) defendant to go free, but doesn’t really want the culprit named. Why? Because the victim was such a reptile, we sympathize with the killer. I consider this tension one of the strengths of the show. Submitted by billp, 1/1/09.

'Uncle Martin's' torture of his niece is based on the still debated idea that intelligence and behaviour are inherited characteristics, and that genetics are inevitable. Not necessarily, since nutrition and environment also play a factor. His attempt to frighten her out of marriage (and one wonders why he cared, but he is, as 'billp' said above, 'despicable'). The now disinherited field of human eugenics, that dated well before WW2 (and in the US) suggested that selective breeding could eliminate 'feeble minded', and 'criminal insanity' from humankind (and, shamefully, certain races). Science fiction writer C.M. Kornbluth wrote two acclaimed stories revolving around this idea, "The Marching Morons", and "Little Black Bag". Describing a future where the stupid had outbred the intelligent ..submitted by MikeReese, 6/9/2012.

Addendum: while it could be said that times have not changed for the better, nowadays, there is one thing, in my opinion, that is a positive change - to borrow the words of another character in a PM episode, the niece would have told Uncle Martin to 'go fly'!! .. submitted by MikeReese, 8/19/2017.

A superior episode, with a satisfying mix of fancy legal footwork and an Agatha Christie-ish use of misdirection. That curved staircase makes its third appearance; at some point the same balusters and newel will be reconfigured into a staircase with a landing that will be one of the most used, if not overused, sets later in the series. The first appearance of the familiar courtroom set with the wood paneled walls, in place of a somewhat less grand room with stone-like walls. That large planter in Perry’s office was in Della’s office three episodes back (Moth Eaten Mink). Distinguished Gentleman has moved from the gallery to the court reporter's desk.
These early shows generally avoid the plot holes we’ve come to expect in later shows, but the doctor’s testimony confuses me. He first assumed Martin succumbed to heart disease, but his autopsy disproved that. Apparently the body was then quickly embalmed without the actual cause of death being determined. DOD 05/11/18

The killer should have just slipped him the saccharin. He could have gotten cancer according to modern-day product warnings! Submitted by Wiseguy70005, 7/06/12.

Was Lt. Tragg's first name established on the series at this point? His door just has "Lieutenant Tragg" written on it and it seems odd that the writers would give another character in a conversation with Tragg the same name as Tragg without an apparent reason or at least mentioning they both had the same name. Tragg even calls the boy "Arthur." Submitted by Wiseguy70005, 7/06/12.
+ The boy is also Arthur in the 1956 novel, where Perry is considerably more generous -- $5 to each of 4 boys and an extra $20 to Arthur, who found the bottle. I don't know when Tragg first became Arthur. Per Wikipedia (Perry Mason (novels)), he first appeared in 1940's TCOT Silent Partner, which also has another character named Arthur. Submitted by (lowercase, with a comma and period) masonite, 07/18/13.

Unfortunately, Christine White does not impress with her acting here; often, PM manages to get some actresses who are able to understate the roles. Christine is not one of these. In her westerns career, she was a better fit. cgraul 7.28.2016
+ Nadine is wearing a wedding band throughout at least the first half of the episode. jfh 17Sep2018
++ Actually, I think it's her engagement ring; in the closeup where she is putting the cyanide tablets into her saccharine bottle you can just barely see what looks like the gem setting at the very bottom of the picture, almost between her ring finger and pinkie. OLEF641 10/20/2020

A Sign of the Times? Early in the episode we see John Locke in his lab working with cyanide. Apparently safety standards weren't as strict then as they are now. Although he his wearing gloves and a lab coat, he has no eye protection, no mask or respirator, and no fume hood. Plus he is working alone. Not only that, he lets his Beloved enter the lab with no protection, then tells her "cyanide's pretty deadly." If the Safety Office had caught me working like that, I would have been written up. I'm reminded of a warning every lab worker has heard:

Johnny was a chemist
Johnny is no more
What Johnny thought was H2O
Was H2SO4.

Submitted by 65tosspowertrap, 3/27/14.

In addition, while doing this dangerous work, Locke uses his teeth to remove the stopper from a test tube he's holding in a gloved hand! Submitted by FredK 31 March2014

"A husband can't testify against his wife," Della advised John Locke, but doesn't that apply to her actions AFTER the marriage? Mike Bedard 4.11.15
+ Yes, per "Exceptions to the spousal testimonial privilege exist where a asked to testify about matters pre-dating the marriage....Privilege Laws Vary From State to State". The preceding exception is also true in California per lowercase masonite, 2/10/16.

DD is a Classic PM episode with respect to (Not) handling the bottle from Westside Lake: he BENDS But does Not BREAK the law about Material Evidence. Mike Bedard 4.11.15

Why the spoiler in the summary? Is that new? I did not want to edit it myself, but it seems odd. - Rickapolis 5/3/17
+ Spoiler?
Was the summary edited after I first made that comment four years ago? Or was I seeing things? I’ll say it was edited, but that’s not to say that is where the smart money is going. Rickapolis 6/21/21
>> No, you weren't seeing things. It looks like the edit occurred no later than the next year (2018). Mini-sleuthed by Notcom, 062221.

On the witness stand Burger asks Locke "Just exactly what is PK3?". Locke answers "Potassium Cyanide". The bottle of potassium cyanide in Locke's lab shows KCN as its chemical formula. I'm no chemical engineer but I don't think PK3 is the formula of anything. Kilo 9/10/2019.
+ Literally translated from the chemical formula, PK3 is "Phosphorus Tri-Potassium"; whether there is such a thing, I have no idea. "PCN" is the proper chemical formula for Potassium Cyanide. It is a salt -- a compound of potassium (K+) and cyanide (CN−) ions. Salts easily dissociate in water, or liquids primarily composed of water, into their component ions, in this case potassium, K+, and cyanide, CN-. Oh, and the symbol K used for potassium (which obviously starts with a "p") is from its Latin name, kalium.
There you go, way more than you ever wanted to know about chemistry! You can learn more about cyanide poisoning here. OLEF641 11/18/21