Chris Hogg has signed a one-year deal with Inverness, with Terry Butcher expressing his shock that the 26-year-old has returned to Caley Thistle.
The 26-year-old had been on a short-term deal at Caledonian Stadium last season but had been on trial with Crewe Alexandra this week.
"I've kept track of him during the summer, but his call to say he wanted to return came right out of the blue," manager Butcher told his club website.
"But it was a superb surprise."
Hogg, who had been with York City, Ipswich Town and Boston United before arriving in Scottish football in 2005, had joined Caley Thistle in January after being released from his contract by Hibernian.
His return to Caley Thistle followed the capture of Wales midfielder Owain Tudur Jones, who left Norwich City, and Austria Under-21 full-back Thomas Piermayr from Linz.
"I'm delighted that Chris has signed a one-year deal as we needed another centre-half and his vast experience will help our younger players," said Butcher.
"I'd been signing younger players, but this week's arrivals are mature, physical players with good experience."
Butcher expressed similar surprise at being able to sign a player of Jones' quality after the Wales midfielder was released from his contract by English Premier League newcomers Norwich.
"He was having a problem at Norwich, not being in their 25, so he needed games," the Caley Thistle boss told BBC Scotland.
"He came to our attention and we wanted him loan, but Norwich decided to pay him up, so we have him on a 10-month contract and he is our player."
"You never dream of getting players like this, because he was on a substantial wage.
"He is a full international and we are just delighted to have someone of that pedigree and that calibre up here."
Jones insisted he was pleased to leave Norwich, despite missing out on their return to the English top flight.
"Just the opportunity to come up here and feel wanted and have the chance to play on a Saturday afternoon," he said of his reasons.
"It is a frustrating thing as a footballer when you train hard all week and you know on a Saturday afternoon you are just going to be watching for the results.
"It is a fresh chapter of my career, a new challenge and in a new league with players I have never played against before.
"You have got to be open to new things. The easiest thing would have been to sit in Norwich and see out the final year of my contract.
"It is a great club with beautiful facilities, but sometimes it is important to step back and look further forward in your career."