Police have arrested a 50-year-old man after a long-running investigation into a $2.7m fraud case against the charity Surf Life Saving New South Wales.

A former senior manager at SLSNSW exploited his position of trust to steal from the charity over 10 years using a “complex” scam, NSW police allege.

The 50-year-old was arrested in Wollongong on Wednesday and is in the process of being charged with more than 50 fraud offences. Detectives say the fraudulent activity spanned the decade from 2006 to 2016.

“It was complex and sustained,” Detective Acting Superintendent Richard Puffett told reporters in Sydney. “These people hold a position of trust and sometimes they exploit that. They are confident, brazen and good at what they do.”

SLSNSW reported the matter to police in early 2017 after noticing anomalies in its accounts. The senior manager – who faces a significant jail term if found guilty – had resigned in mid-2016.

Puffett alleged the scam involved the use of fraudulent invoices for vehicle sales and the setting up of a fake printing company. He said the 50-year-old had spent the funds on his lifestyle and assets.

SLSNSW – which has launched separate civil proceedings against the former manager – welcomed Wednesday’s arrest. “We have been cooperating with NSW Police for the past three years with their investigations and we now await the outcome of criminal proceedings,” its president, George Shales, said in a letter to members.

“We know our members share our anger, disappointment and frustration in this matter and we have endeavoured to keep clubs and other stakeholders informed of progress.”

SLSNSW has appointed internal and external auditors, refreshed its finance and compliance committee and overhauled “governance training” for all board members.

Shales said investigations and reviews had resulted in changes to the organisation “to ensure such a situation cannot arise in future”, with the improvements being endorsed by the Australian Charities and Not-for-profits Commission.