Stebbins was an auror who briefly tailed Newt Scamander for the British Ministry of Magic at some point after Newt refused to take on the task of hunting down Credence. After an hour, Newt was able to shake Stebbins after impeding him by conjuring a strong magical wind (CG).
Muggle passersby were perplexed and entertained when they saw the magical wind blow away Stebbins's hat and nearly knock him to the ground (CG).
Other canon notes and references
Newt's brother Theseus informed Newt that the Ministry was surveilling him after he refused to hunt down Credence (CG).