In 1899 Carvalho sued The Jamaica Bay Turnpike Company to keep them from building a bridge connecting Rockaway Beach to Brooklyn claiming it would "completely destroy the character" of his property.

[14][15] He received a regular salary from the New York Detective Bureau to consult on cases requiring handwriting analysis.

[18] His personal collection contained "items that are representative of ordinary handwriting from the 10th to the 20th centuries, written in English, French, Latin, German, and Dutch.

"[19] The Hartford Daily Courant reported "Sir Conan Doyle stated in a lecture in New York that Mr. Carvalho's powers exceeded those given to Sherlock Holmes."

[22] In 1906 the Keowee Courier called him "the most prominent expert examiner of questioned handwriting, inks and paper in America" after his testimony in a local murder trial.

While he was well-known during his lifetime, his career as a handwriting expert was outlined and further promoted the 1929 book, Crime in Ink, written by his daughter Claire Carvalho and Boyden Sparkes.