As more police departments around the US introduce body cameras, financial ties between police chiefs and a major camera maker are prompting questions about ethics and conflicts of interest.

An investigative report by the Associated Press, published on Tuesday, described several cases of police chiefs around the country becoming consultants for Taser International, after championing no-bid contracts for the company’s body cameras and data storage services. The report highlighted instances of Taser paying for airfares and hotels for serving police chiefs, in exchange for promoting company products at conferences.

One of the chiefs mentioned in the investigation allegedly emailed Taser about persuading another police department to buy its cameras, saying “but my fee is not cheap! LOL.”

Taser's Hiring Of Ex-Chiefs To Promote Body Cams Raises Ethics Questions http://t.co/WTIVXCtMSE — The Crime Report (@TheCrimeReport) March 3, 2015

Albuquerque, New Mexico is investigating the city’s $1.9 million no-bid contract with Taser, when Police Chief Ray Schultz became a consultant for the company after resigning from the force.

New Orleans signed a $1.4 million contract with Taser for body cameras and data storage in December 2013. Police Superintendent Ronal Serpas stepped down in August 2014, and became a consultant for Taser, speaking at company events in Arizona and Canada. Serpas told AP this wasn’t a violation of the state’s ethics laws, because he wasn’t lobbying his former employer.

Taser has been paying for Salt Lake City’s Police Chief Chris Burbank to speak at company-sponsored conferences, but Burbank called the relationship “appropriate” because he never received any speaking fees. According to AP, Burbank “believes he hasn’t violated a city code prohibiting paid product endorsements on public time.”

Emails obtained by AP show that Jeffrey Halstead, police chief of Fort Worth, Texas, worked with Taser last year to help the company meet its first-quarter sales goals. The result was a no-bid contract worth up to $2.7 million for body cameras and data storage. Afterwards, Taser paid for Halstead’s airfare and accommodation at events in Miami, Phoenix and Boston.

Timeline details ties between Fort Worth police chief and Taser International http://t.co/Ro4gsFOEzS — The Associated Press (@AP) March 3, 2015

Halstead left the FWPD in January and set up his own consulting company, telling AP he hopes to become an “official consultant” for Taser and speak at upcoming company events in Australia and the United Arab Emirates.

Luke Larson, Taser’s chief marketing officer, said it was “pretty normal practice for police chiefs and other recently retired individuals to speak on behalf of the industry.”

However, other members of the industry have expressed frustration at having to bid on proposals they say are tailored to Taser products, or be denied bidding opportunities as police chiefs cozy up to Taser.

READ MORE: Obama police task force sidesteps body cameras, wants independent probes of shootings

Body camera use by police has increased dramatically over the past two years, after a string of suspect deaths at the hands of police prompted waves of popular protests. Los Angeles has pledged to equip the entire force with cameras this year, while Seattle has launched a YouTube channel to make redacted bodycam footage available to the public.