Newcastle United have terminated the contract of Fabricio Coloccini by mutual consent, bringing to an end his eight-year spell with the club.
The 34-year-old defender had one more year to run on his deal after signing an extension in 2015.
However, following relegation to the Championship, he has been allowed to leave early so he can join San Lorenzo in his native Argentina.
A former club captain, Coloccini - who was signed from Spanish side Deportivo La Coruna in 2008 - made 275 appearances for Newcastle in all competitions, scoring seven goals.
Coloccini cited family reasons for his departure in a lengthy open letter published on Newcastle's website.
He wrote: "Today I'm taking the decision of taking a step sideways, of leaving, for several reasons, none of which have anything to do with not wanting to play in the Championship.
"As I showed last time we lost our Premier League status, when even though I had a World Cup ahead of me, I still wanted to stay at the club.
"One of the main reasons is that after so many years of trying to achieve a title for the club and not being able to do it, it might be time to let other players arrive with the same drive, impetus and desire as I did years ago.
"For logical reasons, the mental strain of this is much more than the physical. For this reason, this is I think for me, the time to take a step sideways.
"Another very important reason is my children. They have been living in Argentina for a few years, they moved there when they were only little. But now I feel they need the presence of their father to help them find a healthy path and direction in life. Also to enjoy my family and my friends, because I left Argentina being only 17.
"Another point that you will undoubtedly understand because this is a city that lives and breathes football - I am 34-years-old now. I feel really well still physically and I am looking forward to carrying on playing football. This day had to arrive, when I had to return to mi gran querido San Lorenzo de Almagro, my home."