Fourteen months ago they wed in a fairy-tale ceremony at an Alpine castle. On Friday, one of Europe's aristocratic young couples was buried - the princess a victim of an apparent drug overdose, her prince driven to suicide.

Mourned by 150 noble relatives, Prince Ludwig Rudolf of Hanover, a 33-year-old great-grandson of Germany's last emperor, and his 26-year-old bride, Isabelle, were laid to rest in a driving frozen rain in the village of Gruenau, 120 miles west of Vienna.The funeral came 14 months after a lavish five-day wedding in the Alpine castle of Bleiburg in southern Austria, home of the bride, Countess Isabelle von Thurn.

Five months later, as the Austrian tabloid Kurier respectfully phrased it, Isabelle "made a gift" of a son, Otto, to her husband.

On Sunday night, the princely pair again made news. This time, it was gruesome.

After dining with an obscure West German pop group and an unidentified American, Isabelle retired to her bedroom in the couple's home, the so-called "Queen's Villa" in Gmunden, 150 miles west of the capital.

Several hours later, the prince found his wife dead on the bed from what police said was apparently a drug overdose, probably cocaine. The prince, who was "in shock," drove from the house and shot himself in a nearby forest of the Almtal valley, his family said.

Reporters trying to learn more about the dead couple got little out of aristocrats at fashionable Vienna nightspots. Few admitted to knowing the pair, and none discussed the use of what Germans often call the "noble drug" - cocaine, which is blamed here for a record number of fatal overdoses this year.

Police insisted on anonymity this week when revealing that old needle marks were found on the arms of the royal couple and used syringes were confiscated from their home.

Prince Ludwig Rudolf was no stranger to the courtroom. In 1981, according to press reports reluctantly confirmed by Munich state prosecutors, he testified at a drug trial that also involved Rainer Werner Fassbinder, the West German film director who died after a cocaine overdose in 1982.

Asked why he transferred some $20,000 to the account of a suspected cocaine dealer, the prince reportedly told the Munich court the money was to pay for a car.

Last week, state prosecutors in the West German city of Hanover closed another drug trafficking investigation against the prince for lack of evidence.

Word that the investigation was dropped apparently had not reached the prince when he shot himself, Hanover prosecutor's spokesman Klaus Ramberger said.

Newspapers have speculated this may have increased the panic the prince felt when he found his wife dead at 2:45 a.m. Monday.

According to press reports based on police sources, he called his brother in London, Prince Ernst August of Hanover, telling him of his suicide plans and asking him to take care of his son.