Mikaele Salesa is a fence specialising in paranormal artifacts. His current location is unknown, with reports varying between an early retirement, a jail sentence, and being shot after a failed heist from a drug lord. It's currently unknown how he acquires artifacts, with Jonathan Sims mentioning that Salesa appears to have a "talent for it."
Timeline
January 2000 - Vincent Yang is kept unintentionally imprisoned in a wooden crate by Mikaele Salesa (and possibly Captain Nathaniel Lukas) after impounding cargo going through Portsmouth. (MAG 66)
Spring 2010 - Dr. Neil Thompson sells an antique syringe, allegedly belonging to John Snow, to Mikaele Salesa (MAG 45).
Early 2011 - Lee Rentoul puts a curse on Paul Noriega after unwillingly spending 5 years in prison for him with the help of a old woman named Angela from Bexley. After Rentoul kills Noriega (at a meeting with Mikaele Salesa), the curse passes to him, causing him to progressively lose parts of his body (MAG 14).
May 2012 - Andre Ramao, having bought a Chinese urn from Mikaele Salesa, begins inexplicably losing items, with no record of them ever having existed. When Salesa is consulted about the urn, he tells Ramao that "[I] don't remember owning it, which means it belongs to you". Ramao becomes progressively more obsessed with the urn, until he falls asleep in front of it, when all the items are returned. After fleeing pale, filthy hands pushing themselves out of the urn, Andre's husband disappears (MAG 38).