The Wiltshire Police officer currently in Salisbury District Hospital has been named as Detective Sergeant Nick Bailey.
Nick joined Wiltshire Police in 2002 and is a well-liked character within the force.
He remains in a serious but stable condition and Temporary Chief Constable Kier Pritchard has visited Nick in hospital today along with his wife.
Kier Pritchard said: "I have visited Nick in hospital this afternoon and I can confirm that he is conscious, talking and engaging with people. Of course, he still remains in a serious, but stable, condition, but I am deeply relieved to have visited him and spoken with him in person.
"I have also met with Nick's family and relayed our deep concern for their welfare.
"We have all been deeply appreciative of the outpouring of support from staff, public and around the country - we are very grateful for this.
"I would like to reassure you all that Nick is receiving medical intervention and care from highly specialist medical practitioners experienced in these matters.
"Nick is a hugely popular member of staff and all our thoughts are with him. The welfare of all of my officers and staff is of paramount importance to me.
"As announced by the Counter Terrorism Network yesterday, it has been ascertained that the substance involved was some form of nerve agent.
"Officers who were first on the scene displayed selfless commitment to their jobs as they tried their very best to help these two people - unaware of what they were dealing with.
"At the time of the first emergency calls no one knew what developments this investigation would take and I would like to commend all officers, staff and volunteers who respond to emergency calls, every day, never knowing what is around the corner as they keep our communities safe.
Police and Crime Commissioner for Wiltshire and Swindon Angus Macpherson said: "This is an unprecedented situation, and I'm very proud of the way in which Wiltshire Police have handled themselves since this occurred on Sunday.
"The way in which they have worked alongside our partners and the Counter Terrorism Policing Network is commendable.
"My thoughts and prayers continue to be with Nick who is still receiving treatment in hospital and his family. I am pleased to hear from the Chief Constable that he was sitting up and talking today.
"It shines a light on the fact that day in and day out our officers, staff and volunteers put themselves in harm's way in order to keep the public safe.
"In the past few days they have worked an incredible amount of hours and together with our partners we are committed to ensuring the safety of the public in Salisbury and Wiltshire."