Shortly after Gardestad's return to Sweden in 1986, the Prime Minister of Sweden, Olof Palme, was murdered. Gardestad was wrongly mentioned in the Swedish media as "the 33-year-old", a suspect in the investigation of the assassination, which severely affected him although Gardestad was on vacation in Greece at the time of the murder, and although he was never questioned by the Swedish police nor was under suspicion by the authorities, the speculations and rumours followed him and his family for the rest of the 1980s. A few years later, he was again the subject of rumours accusing him of being Lasermannen, a bank robber and serial killer. The rumours affected the sensitive and already unstable former star, and Gardestad withdrew and fell into a deep depression.  In the early 1990s, Gardestad was briefly coaxed out of retirement by his friend and fellow Swedish pop singer Harpo. He joined Harpo on a concert tour and made guest appearances. In 1992, they released the duet "Lycka" ("Happiness") as a single; it garnered little attention but marked Gardestad's return to music. Early that year he embarked on his first tour since 1978 and played a series of dates with Plura Jonsson, Tove Naess, Totta Naslund and Dan Hylander, and received overall positive reviews from the press.  In 1993, a compilation album titled Kalendarium 1972-93 was promoted by a tour in the Swedish folkparks; the album and tour were successful, as was his first composition in twelve years, "For karlekens skull" ("For Love's Sake"), which topped the Svensktoppen chart. The Kalendarium collection included a Swedish-language re-recording of the title track from Blue Virgin Isles, "Himlen ar oskyldigt bla" ("The Sky is Innocently Blue"), which fifteen years after its original release became another Svensktoppen hit, and became one of his best-known songs. In early 1994, Kalendarium 1972-93 was awarded a platinum disc. All of Gardestad's albums from the 1970s and early 1980s, with the exception of Blue Virgin Isles, were re-released on CD by Polar, and a generation of Swedes who grew up listening to his music now re-discovered and re-evaluated his back catalogue as adults. His body of work has since come to be regarded as a national treasure as important as those of Evert Taube, Carl Michael Bellman and Cornelis Vreeswijk both by fans and Swedish music critics.

Answer this question "What happened then to Gardestad?" by extracting the answer from the text above.
severely affected him although Gardestad was on vacation in Greece at the time of the murder,