Hi Pedro, I don't know the name of your ancestor, but I met a Tesch (a lawyer/contador) in Petropolis some five years ago (I was coincicentally living in Belo Horizonte from 1993 to 2000, and was visiting the city of Petropolis as a passeo). I returned to Luxembourg where my (rather small) family stems from, and we have a genealogical tree which goes back as far as the 16th century.
The Tesch I talked to in Petropolis (I forget his first name) said that his family moved from Germany to Brasil in the 1840s when the emperor Pedro II built the Petropolis summer residence. He appeared to know that his ancestor had arrived in Brasil as a qualified labour contracted for the purpose of the building. Anyway, you have today a dozen of Tesches in Petropolis. Are you related to them?
Besides I had the pleasure in 1999, of bumping into a very beautiful young lady named Carolina Tesch. Incidentally she was Brasilian Playboy Bunny of the same year. I had only the opportunity to talk to her on the phone, as she was working for the same company as myself in Porto Alegre, on a temporary basis. She said that her family is located in Caxias do Sul (RS), but didn't know anything about her ancestry.
Please feel free to contact me in case you need any further information.