Had a closer look in my files and found a letter from "Haldens Historiske samlinger (HHS)" with regards to Ohlgren. A translated and shortened quote from the letter; "A local historcal person Forstrøm mentions in his notes that Martin was serving with Wolhardt a tanner ("Garver") as a tanner trainee...

Hi, Im also an Ohlgren related person. My mother had Ohlgren as her lastname before she got married. She was born In Halden. As a matter of fact, in my register i have a person named Lorentz Andreas Ohlgren, born 1814. According to my records, his mother was called Maria Andersdatter and was married...