WASHINGTON - New details are emerging on Friday about the death of a U.S. Capitol police officer who died after an attack on the Capitol building earlier in the week.READ MORE: US Capitol police officer dies of injuries sustained during pro-Trump riots, officials sayOfficer Brian Sicknick succumbed to his injuries on Thursday.According to an EMS report, they were called to a possible cardiac arrest when they found Sicknick "unresponsive" and struggling to breathe.READ MORE: US Capitol flags ordered flown at half-staff for fallen US Capitol Police Officer who died following riotThey believed he suffered a head injury, but also found evidence of "suspected exposure."AdvertisementFOX 5’s Lindsay Watts reports that the suspected exposure.