This may have been covered in the books, but I don't remember it.

Tom made the Diary Horcrux when he was ... what, about sixteen?
I *think* I remember that he had to commit a murder to do the soul work. Who did he kill? Not Myrtle; she was killed by the Basilisk, and with no time for an elaborate ritual. (Actually, JKR doesn't do much ritual magic, does she?) No other student was found dead, so who disappeared?

He could have made the Diary either during the summer while he was living with the muggles or during the school year while at Hogwarts. There are advantages and disadvantages to both locations.
In a murder mystery, disposal of the body is usually the biggest problem. Riddle had the Basilisk, so he got to skip that hurdle if he was at Hogwarts. If he made the Diary over the summer, then he *did* have a corpse to deal with, not to mention the underage magic sensors.

Riddle would have a lot more unsupervised time during the summer. As an scary-psycho near-adult, he probably only needed to make bed check. He would have had chores, but he could bully other kids into doing the work for him. Most of his day time was his own. There is little truly free time at Hogwarts; classes, curfew, and meals are mandatory. He was popular with the faculty and many students: his absence would have been noticed.

Traditionally, a "sacrifice" has to be of value To The Caster.
You don't sacrifice your garbage or that weird whatchamacallit your great-aunt found at a yard sale and dumped on you. Did he kidnap some acquaintance at Hogsmeade? If someone had disappeared during a Hogsmeade weekend, suspicion would have fallen on the School immediately. With Myrtle's death, the school was already tense. Myrtle was treated as a tragic accident. Hagrid was framed and expelled for having a killer pet, but another corpse would have called down a major investigation, and a lot more heat than Riddle could handle. Riddle had tortured some children while he was still at the orphanage. He got away with it, but he had a bad reputation there. If someone (especially a known enemy) had disappeared, Tom would have been suspected. Did he grab a homeless woman off the street? It wouldn't have cost much money to rent a car and drag his victim to an abandoned warehouse or to some secluded spot that was out of the city entirely. He could have looked up spells to stymie any forensic teams. On the other hand, the Chamber of Secrets had assured privacy.

I am going to presume that ripping your soul in two pieces and taking one piece out of your body is a highly unpleasant and debilitating process. Surely he had designated a place to recover.

Tom would have planned for a period of recuperation: he would have minimized his vulnerability. If he was at Hogwarts, then he probably was in the Chamber of Secrets from well before beginning the ritual until he had recovered enough to act pretty normal. He hated that orphanage the way a ex-convict hates prison: I can't see him trusting any hiding place there.

I'm pretty sure that he made the Diary horcrux at Hogwarts, but who was his first premeditated murder in the School or Hogsmeade?

 

Do you remember a murder of the Riddle Family? Three people killed by Riddle himself.

I can't recall if there is evidence that they were used as a material for the Voldemort's first horcrux, but it'd be pretty logical and obvious.

He was still underage back then, proficient enough in Dark Arts to use an Avada Kedavra, skilled enough in Legillimency and/or Memory Charms to alter Gaunt's memories to set him up, so why not?

He probably had necessary skills to do so and, in my opinion, eliminating his muggle father would be a great start to his immortality quest, don't you think?

Of course, it could have been done while being furious about discovering that his worthless muggle father was still alive and done without any planning on his part, but it'd shatter my image of Thomas Riddle's early years, so I'll choose a variant number one.

E.A.

P.S. I'll go and check HBP - maybe Dumbledore had some evidence, because I remember that they discussed a murder itself, but can't recall if they covered a possibility of horcrux creation. I'll edit after finding out.

[EDIT] Beside getting a giant headache after reading chapters when they discussed murder itself and Thomas' horcruxes, I didn't find anything useful. I will check out HP-Lexicon - maybe there is some info.

[EDIT2] I didn't found there anything.

[EDIT3]Ehh... I reread once again a dialogue between Slughorn and Tom about horcruxes and he had Gaunt's ring already, and with the fact, that he was asking how to do a horcrux, I can only say - either my theory is worthless, or he was setting up Slughorn to tell him about multiple horcruxes.

E.A.

 

When did he kill the Riddles? He probably tracked them down using the information on his birth certificate. That's moderately impressive, considering his lack of resources; no money and no connections.

Did he actually cast at least three AK's successfully at age sixteen? It just seems, well, not wise to for him to make creating his first horcrux be such an elaborate plot. Not that Tom ever lacked hubris. Still, for an amateur (if I may use that term here) the best plans are simple ones.

Remember "Silence of the Lambs?" They said something to the effect that the first victim of a serial killer was the one that had the most relevance. I bet you're right - Riddle, Sr. was probably the first murder planned for a horcrux. It seems odd that Dumbledore would completely overlook that aspect.

Tearing your soul HAS to be a deliberate act, or every wizard who ever killed someone would have a horcrux. The DE's would have dozens, each, at the very least. Vodemort would have literally scores of them.

From what I remember of the books, Tom Riddle was well on his way to murderous psychosis long before he started at Hogwarts. JKR's position is that the Gaunts had managed to inbreed mental instability into their line. The implication that he would have been ... y'know ... evil even if he had never heard of magic, that he was corrupt even as a little kid, is frightening.

Maybe Tom Sr.'s refusal to acknowledge his by-blow was actually well-founded.

 

Riddle had the Gaunt ring with himself when he was talking to Slughorn about horcruxes, and (in Polish version) is mentioned that he's a prefect, so it'd determine a time of Riddle murder as a summer before Voldemort's 5th, 6th or 7th year.

As for tracking them via his birth certificate. He didn't have to do so, because he was told about his father by Morfin Gaunt, who initially thought that Tom Sr. arrived to his house (HBP, chapter 17th).

I remember that Dumbledore mentioned that Riddles were killed by Avada Kedavra, so yeah, he had done it three times. Of course we can't also forget that he altered Morfin's memory, so the guy admitted that he was guilty of this mess. Cannon!H. Potter compared to Thomas is just a pitiful wizard, who learned a few spells and can't execute them properly.

E.A.

 

Dumbledore said that Voldemort killed the Riddles in the summer after his 5th year, the year after he released the Basilisk. That's when, I think, he made the Diary-horcrux. He got the Locket and Hufflepuff's cup from an older woman while he was working at Borkin and Burkes after school, and i think that he used her death to make another horcrux. He turned the ring into one at some time. It's commonly believed that Nagini is a horcrux, but I don't think that there's any basis behind that.

 

I think you're missing a point. I think he already had two horcruxes (diary and ring) when he talked to Sluggy. Think about it, he wasn't asking just about multiple horcruxes, he was asking about Seven sould fragments. I think he already had discovered three fragments made him powerful by then and wanted some soul/arithmancy advice more than horcrux advice specifically. Likely he made two before then out of paranoia (always have a backup to your backup, redundancy keeps you alive), and stumbled quite accidentally over this power boosting aspects of the magic (since three is very important).

Yes it's possible that he created them from the Riddle family (killing your father and half brother ought to be pretty high up the sacrifice scale), but I doubt it. It just seems like they were a rush job, muggles living better than an ancient noble wizarding family must have really pissed him off, and the frame up, through adequate, was a bit rushed. More likely we never heard about his first victim because nobody cared.

London is full of people nobody would miss and Tom was literally sitting on the source. Surely it's likely that some orphans never got adopted and were turfed out once they came of age. A former bully who disappeared one day just before or after he was supposed to leave the orphanage would never be missed and Tom would have all the time in the world to perform a slow and painful ritual death. If not, there's plenty of homeless people and transients. These were not necessarily vengance killings, these were murders with a purpose and he could take his time picking a victim that would not result in him getting caught. Sure he could go cast a quick AK at people who annoyed him and frame up someone else for it any time he wanted, but these murders were more likely to be more like a surgical procedure than a passionate act of rage.

As for body disposal, I think that one is easy. Barty Crouch showed us how to get rid of a body in GoF. Transfigure to a bone and bury. If no one was missing there'd be little reason to bother.

 

Actually, there is a basis - Dumbledore actually mentions to Harry that he believes Nagini is a Horcrux in HBP.

-J

 

No I meant three soul fragments, two horcruxes (diary and ring, both pre-sluggy artifacts) and his body. Why two? Because one could be destroyed and he wanted the safety net a spare provided.

A horcrux is obviously a last ditch effort in the first place. A person that makes a horcrux is someone who first has to admit "they are going to get me, eventually". If he really was invincible, the most powerful wizard, and the best dueler he would have no need for a horcrux. Instead he admits that whether it takes five Aurors or fifty, his enemies won't stop until he is dead. So he creates a backup and tells his most trusted friend/follower just in case...

But a clever enemy might expect him to create this horcrux or his followers might betray him. What's a man to do? He needs a way his faithful followers can bring him back if the Aurors win, but he also needs a safety in case his followers betray him. Two horcruxes... One hidden away, the other where his most faithful can get to it. Likely at first the ring was his "public horcrux" as he wore it proudly while his diary was a very private affair. Later when he had spares, the ring disappeared while Lucius got the diary.

And why is everyone so obsessed about the Riddles? So they are his only known victims but that really doesn't mean anything as I already proved. He lived in a home for the unwanted, in a city where homeless beggars have been plentiful since the middle ages. Furthermore this was the height of the Blitz, London was getting the shit kicked out of it! Either one of these conditions could make a ready source of ideal victims that we would never have heard about. Why would Dumbledore here about them? He only knew about the Riddle family because they were Voldemort's family! Hundreds of muggles died or went missing every day in that time. Unless Tom was messing with his family or with other wizards, he almost certainly had carte blanche.

 

The Diary was designed to eventually possess anyone who spent a significant length of time writing in it. Ginny had it (and used it) for most of the school year, but I don't remember anyone noticing that she was having any problems til spring. Of course, everyone was distracted by all the petrified students.

Would the locket and ring take over someone who simply wore them? Tom habitually wore the ring - was he immune, or would he have eventually resorbed (that may the first time that word ever has been used in this context) the soul fragment? Is the difference that the Diary was interactive, and thus would have an easier entry into the victim's psyche? Or do souls actually have sizes, and half a soul would be more ... energetic ... than later (smaller) fractions?