Regana Tosh
Regana Tosh was a Markalian smuggler operating in the 2370s. Regana Tosh was a known felon and was considered dangerous. He was convicted of trafficking in jewels of sound on stardate 45858 and served a three-year sentence at the Kar Zartkaar detention facility. 

In 2372, he traveled to Deep Space 9 where he attempted to sell Tallonian crystals. Constable Odo hoped he could use Regana Tosh to infiltrate the Markalian smuggling operation. However, the operation failed when Worf intervened. Worf was finding it difficult to adjust to life aboard Deep Space 9 versus his life as security chief aboard the . As such, Odo was only able to arrest Tosh, the middleman, instead of taking down the whole smuggling operation. ()

Background information 
Regana Tosh was played by Roderick Garr. He was referred to consistently in the script as "Shady Alien".

The information in the last paragraph of Worf's PADD, which featured information about the criminal from Markalian Law Enforcement, was barely readable. On that PADD he was identified as Jadwel Tarmak even though the picture clearly showed the alien sitting at the bar (who was later identified as Regana Tosh). It is likely that his name was changed during production and wasn't changed accordingly on the PADD, or that the people working behind the scenes just thought the information on the PADD wouldn't be legible on the TV screen.

Due to a typographical error, the stardate was listed as 4585.8, rather than the correct stardate 45858, which would mean he finished his sentence sometime during DS9 Season 3.

"Jewels of Sound" seems to be a reference to Harlan Ellison's original draft of .

Markalians