The old man opened the small bundle he had brought and took out a leather folder. It contained a set of thin knives with short blades and long handles. He selected one that had a fine, hair-sharp blade.
Then he took a square pad of white paper from his sleeve and put it on the corner of the desk. He picked up with a pair of pincers the plum the mouse had eaten from and laid it on the pad. With remarkable dexterity he cut from its flesh a slice as thin as the thinnest tissue paper.
The judge and his two lieutenants eagerly followed his every movement.
The coroner smoothed out the slice on the pad using the blade of the knife. He peered intently at it. Then he looked up and asked for a cup of boiled water, an unused writing brush, and a candle.
When a clerk had brought the required materials, the coroner moistened the brush and soaked the thin slice in water. Then he took a small square piece of very white, glazed paper, spread it out over the slice and pressed it with the palm of his hand.
The coroner lighted the candle. He took up the glazed paper and showed it to the judge; it bore the wet imprint of the slice. The coroner held it over the flame till it had dried.
He took the paper over to the window and scrutinized it for some time, softly running his forefinger over it. Tao Gan left his chair and looked over the coroner's shoulder.
The coroner turned round and handed the paper to the judge. He said:
"I beg to report that this plum contains a large dose of a poisonous dye called gamboge. It was introduced by means of a hollow needle."
Judge Dee slowly caressed his whiskers. After a glance at the paper he asked: "How do you prove that?"
"This method", the coroner said with a smile, "has been used in our trade for many centuries. The alien matter in the juice of the plum is recognized by its colour and granulation. If Your Honour observes this imprint, a yellow tinge will be clearly recognisable. The difference in granulation can be noticed only by the sensitive fingers of an experienced drug dealer. Since the slice shows a number of small round spots I conclude that the gamboge was introduced by means of a hollow needle."
"Excellent work!", the judge said approvingly. "You will now examine the other plums."
As the coroner set to work Judge Dee idly played with the empty cardboard box. He pried loose the folded white paper that covered its bottom. Suddenly he bent over it and peered intently at a faint red mark on the edge of the paper.
"Well, well", he remarked, "what a careless thing to do!"
Sergeant Hoong and Tao Gan rose and eagerly bent their heads over the paper. Judge Dee pointed with his forefinger at the red mark.
"That is half of Woo's seal!", the sergeant exclaimed. "The same seal as the one he impressed on the picture the other day!"
The judge leaned back in his armchair.
"Thus two clues point straight to our painter", he said. "First, the poison used. Gamboge is used by all painters as a yellow pigment and they are familiar with the fact that it is dangerous poison. Second, this sheet of paper employed as filling of the box. I suppose that Woo once used it as support for impressing his seal on a picture; inadvertently half of the seal impression was transferred on this paper underneath."
"This is the sort of thing we have been waiting for!", Tao Gan exclaimed excitedly.
The judge did not comment. He waited silently till the coroner had completed his examination of the other plums.
Finally the old man reported:
"Everyone of these contains a lethal dose of gamboge, Your Honour!"
The judge selected a sheet of the official writing paper on his desk and pushed it over to the coroner.
"Please record your testimony on this paper!", he ordered, "and affix your thumbmark to it!"
The old coroner moistened his brush and filled out the document. After he had affixed his thumbmark to it the judge dismissed him with a few kind words. Then he ordered, a clerk to call Headman Fang.
When the headman came in Judge Dee ordered curtly:
"Take four constables and arrest the painter Woo Feng!"
Fifteenth Chapter
Three beats of the large bronze gong resounded through the tribunal announcing the opening of the afternoon session.
A fair crowd of spectators had assembled in the court hall. The old General Ding had been a well-known resident of Lan-fang.
Judge Dee ascended the dais. He ordered Candidate Ding to come forward.
As he was kneeling in front of the bench Judge Dee spoke:
"The other day you appeared before this tribunal and accused Woo Feng of having murdered your father. I have made a painstaking investigation and assembled evidence that warranted Woo's arrest. Yet there are not a few points that need clarification.
I shall now hear the accused and you will listen carefully. If there should come up any point concerning which you can supply additional information, you shall not fail to speak!"
Judge Dee filled out a slip for the warden of the jail. Soon two constables led Woo into the court hall. As he approached the dais Judge Dee noticed that he looked quite unperturbed.
Woo knelt and waited respectfully till the judge addressed him.
"State your name and profession!", the judge said curtly.
"This insignificant person", Woo replied, "is called Woo Feng. I am a Junior Candidate by profession and a painter by preference."
"You", said the judge sternly, "are accused of having murdered General Ding Hoo-gwo. Speak the truth!"
"Your Honour", Woo said calmly, "I emphatically deny the accusation. I am familiar with the victim's name and the crime for which he was dismissed from military service because I often heard my father speak about that disgraceful affair. But I beg to state that I have never met the General. I did not even know that he was living in Lan-fang until his son started to spread malignant rumours about me. Those rumours I totally ignored since they were so ridiculous as to make refutation quite unnecessary."
„If that is so", Judge Dee said coldly, "why then did the General stand in constant fear of you? Why did he keep the gates of his mansion closed day and night and confine himself to his locked library? And if you did not plan some foul scheme against the General, why did you hire ruffians to spy on his mansion?"
"As to Your Honour's first two questions", Woo replied, "they concern the internal affairs of the Ding mansion. Since I am completely ignorant of such things, I am in no position to express any opinion. As regards the last query, I deny ever having hired any people to spy on the Ding family. I challenge my accuser to produce one of those men I allegedly hired and confront him with me!"
"Don't be too sure, young man!", the judge said sternly. "As a matter of fact I have already apprehended one of those ruffians. You will be confronted with him in due time!"
Woo shouted angrily: "That scoundrel Ding bribed him to give false testimony!"
When he saw that at last Woo had lost his temper, Judge Dee thought to himself that this was the right moment to spring another surprise on the accused.
He leaned forward in his chair and said sharply:
"I, the magistrate, shall tell you why you hated the Ding family! Not because of the feud between your father and General Ding. No, you had a quite personal and despicable motive. Look at this woman here!"
While he was saying this the judge had taken from his sleeve a section cut out of Woo's painting showing only the face of the goddess Kwan Yin.