It supposedly happened during the match against Cardiff City 10 days ago.
An investigation was launched after a necklace, understood to be worth thousands of pounds, was taken from the private changing area.
But the jewellery, which is understood to belong to a Newcastle United player, was not reported stolen until Thursday.
Newcastle have tried to keep the story quiet, because they could not work out if it was mis-laid, lost, stolen ... or if there was a necklace in the first place!
A spokesman for NUFC said the club did not want to comment on the matter and would not be identifying which player the necklace belongs to.
It's not the first time this has happened.
Jermaine Jenas once had his goldfish stolen, and Mick Quinn had six pork pies and box of Mars bars taken from his lunch box.
NEWCASTLE UNITED 2009/10
SHAMROCK ROVERS 0 NEWCASTLE UTD 3 (S Taylor, Ameobi, Ranger)
Steve Harper, Habib Beye, Callum Morris, Fabricio Coloccini, Tamas Kadar, Wesley Ngo Baheng, Nicky Butt, Joey Barton, Damien Duff, Kevin Nolan, Nile Ranger
Subs: Jose Enrique, Danny Guthrie, Ryan Taylor, Alan Smith, Shola Ameobi, Steven Taylor, Frank Wiafe Danquah, Ole Soderberg, Ben Tozer, Kazenga LuaLua, Tim Krul, Ryan Donaldson
DARLINGTON 2 NEWCASTLE UTD 7 (Duff, Nolan, Gutierrez, S Taylor, Carroll, Ameobi 2)
Krul (Forster, 46); R Taylor, Beye (Coloccini, 46), S Taylor, Kadar (Enrique, 46); LuaLua (Guthrie, 46), Barton (Butt, 46), Nolan (Xisco, 59), Smith (Donaldson, 59), Duff (Gutierrez, 46); Ameobi (Carroll, 46).
HUDDERSFIELD 0 NEWCASTLE UTD 1 (Nolan)
Harper, Coloccini, Enrique (Donaldson 80), Barton (Smith 58), Guthrie (Tavernier 80), Gutierrez (Duff HT), Xisco (Ameobi HT), Beye (Kadar HT), Taylor S (Taylor R HT), Lua-Lua (Adjei 73), Carroll (Nolan 58).
ORIENT 6 NEWCASTLE UTD 1 (Barton pen)
Krul (Forster, 46); Beye (Tozer, 80), S Taylor (Lough, 80), Coloccini (Geremi, 46), Enrique (Kadar, 73); Gutierrez, Barton (Xisco, 46), Smith (Guthrie, 60), Duff (LuaLua, 73); Nolan; Martins (Carroll, 46).
NEWCASTLE UTD 0 LEEDS UTD 0
Harper, Beye, Bassong, S Taylor, Enrique, R Taylor, Smith, Barton, Gutierrez, Ameobi, Carroll Subs: Coloccini, Nolan, Xisco, LuaLua, Krul, Donaldson
DUNDEE UTD 1 NEWCASTLE UTD 1 (Carroll)
Harper; R Taylor, S Taylor, Kadar, Enrique; Gutierrez, Barton (LuaLua, 75), Smith, Duff (Geremi, 88); Nolan; Carroll.
WEST BROM 1 NEWCASTLE UTD 1 (Duff)
Harper (Krul 46), Ryan Taylor, Steven Taylor,Coloccini, Jose Enrique, Gutierrez, Smith, Nolan, Duff,Ameobi (Ranger 90), Carroll (Barton 75).
Subs Not Used: Xisco, Geremi, LuaLua, Kadar.
NEWCASTLE UTD 3 READING 0 (Ameobi 3, 1 pen)
Ryan Taylor, Steven Taylor, Coloccini,Jose Enrique, Nolan, Barton (LuaLua 82), Smith (Geremi 78),Gutierrez, Ameobi (Xisco 77), Carroll.
Subs Not Used: Krul, Kadar, Ranger, Donaldson.
NEWCASTLE 1 SHEFF WED 0 (Ameobi)
Harper, Simpson, Steven Taylor, Coloccini,Jose Enrique, Ryan Taylor (Guthrie 89), Nolan, Smith,Gutierrez, Ameobi (Ranger 87), Carroll (Xisco 58).
Subs Not Used: Krul, Geremi, LuaLua, Kadar.
CRYSTAL PALACE 0 NEWCASTLE 2 (Nolan, R Taylor)
Harper, Simpson, Coloccini, Steven Taylor,Jose Enrique, Ryan Taylor (Butt 65), Nolan, Smith,Gutierrez (Geremi 89), Guthrie (Ranger 66), Ameobi.
Subs Not Used: Krul, Xisco, LuaLua, Kadar.
NEWCASTLE 4 HUDDERSFIELD 3 (Guthrie, Geremi, Ameobi (pen), Nolan) CARLING CUP
Krul, Simpson, Geremi, Kadar, Jose Enrique, Ryan Taylor, Guthrie, Butt (Ameobi 46), LuaLua (Gutierrez 65), Nolan, Ranger, Ameobi (Vuckic 90).
Subs not used: Harper, Smith, Tozer, Donaldson.
NEWCASTLE 1 LEICESTER 0 (Guthrie)
Harper, Ryan Taylor, Steven Taylor, Simpson,Jose Enrique, Geremi, Barton (Kadar 89), Nolan,Guthrie (Donaldson 85), Smith, Ranger (Vuckic 85).
Subs Not Used: Krul, LuaLua, Ngo Baheng, Tozer.
CARDIFF CITY 0 NEWCASTLE 1 (Coloccini)
Harper, Simpson, Coloccini, Steven Taylor, Jose Enrique, Guthrie (Lovenkrands 61), Barton (Geremi 86), Smith, Ryan Taylor (Butt 76), Nolan, Ranger.
Subs Not Used: Krul, LuaLua, Kadar, Donaldson.
BLACKPOOL 2 NEWCASTLE 1 (Carroll)
Harper, Simpson, Steven Taylor, Coloccini,Jose Enrique, Ryan Taylor (Geremi 66), Butt, Nolan,Barton (Ranger 83), Carroll, Guthrie (Lovenkrands 66).
Subs Not Used: Krul, LuaLua, Kadar, Donaldson.
NEWCASTLE 3 PLYMOUTH 1 (S Taylor, Nolan, Carroll)
Harper, Simpson (Ryan Taylor 30), Steven Taylor,Coloccini, Jose Enrique, Geremi, Barton (Guthrie 59), Smith,Lovenkrands (Ranger 59), Nolan, Carroll.
Subs Not Used: Krul, Khizanishvili, Butt, LuaLua.
(Carling Cup) PETERBOROUGH 2 NEWCASTLE 0
Krul, Tavernier, Steven Taylor, Tozer, Ryan Taylor,LuaLua (Smith 59), Guthrie, Donaldson (Geremi 60), Lovenkrands,Ranger, Vuckic (Nolan 60).
Subs Not Used: Soderberg, Ngo Baheng, Shane Ferguson, Inman.
IPSWICH 0 NEWCASTLE 4 (Nolan 3, Ryan Taylor)
Harper, Steven Taylor, Khizanishvili,Coloccini (Lovenkrands 68), Jose Enrique, Smith, Nolan, Butt,Ryan Taylor (Donaldson 78), Carroll, Ranger (Harewood 65).
Subs Not Used: Krul, Ngo Baheng, Tozer, Vuckic.
NEWCASTLE 1 QPR 1 (Harewood)
Harper; Simpson, S Taylor, Khizanishvili, Enrique; Guthrie (Lovenkrands, 88), Smith, Nolan, Butt (Gutierrez, 46); Ranger (Harewood, 61), Carroll.
Subs not used: Krul, Kadar, Donaldson, Geremi.
NEWCASTLE 0 BRISTOL CITY 0
Harper, Simpson, Steven Taylor, Khizanishvili,Ryan Taylor, Guthrie (Ranger 85), Smith, Nolan,Gutierrez (Carroll 65), Harewood, Lovenkrands.
Subs Not Used: Krul, Geremi, Butt, Kadar, Donaldson.
NOTTINGHAM FOREST 1 NEWCASTLE 0
Harper, Ryan Taylor, Simpson, Khizanishvili, Jose Enrique, Guthrie, Nolan, Smith, Lovenkrands (Gutierrez 61), Harewood (Ranger 83), Carroll.
Subs Not Used: Krul, Geremi, Butt, Kadar, Donaldson.
SCUNTHORPE 2 NEWCASTLE 1 (Nolan)
Harper, Ryan Taylor, Khizanishvili, Simpson, Jose Enrique, Guthrie (Ranger 86), Geremi (Harewood 61), Smith, Gutierrez, Nolan, Carroll.
Subs Not Used: Krul, Tozer, Kadar, Lovenkrands, Donaldson.
NEWCASTLE 2 DONCASTER 1 (Carroll, Nolan)
Harper, Ryan Taylor, Kadar, Khizanishvili, Jose Enrique, Guthrie, Butt, Nolan, Gutierrez (Tozer 87), Carroll, Harewood (Ranger 60).
Subs Not Used: Krul, Lovenkrands, Geremi, Ngo Baheng, Donaldson.
SHEFF UTD 0 NEWCASTLE 1 (R.Taylor)
Harper; Simpson (Ranger, 76), Coloccini, Kadar, Enrique; R Taylor, Nolan, Butt, Smith, Gutierrez (Harewood, 85); Carroll.
Subs: Krul Guthrie, Geremi, Tozer, Donaldson.
NEWCASTLE 3 PETERBOROUGH 1 (Gutierrez, Carroll, Simpson)
Harper, Simpson, Steven Taylor, Coloccini, Jose Enrique, Guthrie, Nolan, Smith,Gutierrez (Ryan Taylor 21), Carroll (Lovenkrands 78), Harewood (Ranger 77).
Subs Not Used: Krul, Geremi, Butt, Kadar.
PRESTON 0 NEWCASTLE 1 (Nolan)
Harper, Simpson (Kadar 65), Steven Taylor, Coloccini, Jose Enrique, Guthrie (Lovenkrands 90), Smith,Nolan, Gutierrez, Harewood, Carroll (Ranger 62).
Subs Not Used: Krul, Geremi, Pancrate, Donaldson.
NEWCASTLE 3 SWANSEA CITY 0 (Harewood 2, Lovenkrands)
Harper (Krul 46), Simpson, Steven Taylor, Coloccini, Jose Enrique, Guthrie (Pancrate 76), Smith, Nolan, Gutierrez, Harewood (Ranger 68), Lovenkrands.
Subs Not Used: Khizanishvili, Ryan Taylor, LuaLua, Kadar.
NEWCASTLE 2 WATFORD 0 (Lovenkrands, Pancrate)
Harper, Simpson, Steven Taylor, Coloccini, Jose Enrique, Guthrie (Pancrate 71), Smith, Nolan, Gutierrez, Harewood (Carroll 56), Lovenkrands (Butt 65).
Subs Not Used: Krul, Khizanishvili, Ranger, Ryan Taylor.
COVENTRY CITY 0 NEWCASTLE 2 (Ameobi, Ranger)
Harper, Simpson, Steven Taylor, Coloccini, Jose Enrique, Pancrate (Ryan Taylor 76), Butt, Smith,Gutierrez, Lovenkrands (Ranger 64), Ameobi (Harewood 64).
Subs Not Used: Krul, Guthrie, Khizanishvili, Kadar.
BARNSLEY 2 NEWCASTLE 2 (Nolan, Harewood)
Harper, Ryan Taylor, Steven Taylor, Coloccini, Jose Enrique (Khizanishvili 80), Pancrate (Ranger 79), Smith, Butt, Gutierrez (Harewood 69), Nolan, Carroll.
Subs Not Used: Krul, Lovenkrands, Simpson, Ameobi.
NEWCASTLE 2 MIDDLESBROUGH 0 (Harewood, Ameobi)
Harper, Simpson, Steven Taylor, Coloccini,Jose Enrique, Guthrie, Nolan, Smith (Butt 49), Gutierrez,Harewood (Ranger 66), Ameobi (Pancrate 83).
Subs Not Used: Krul, Lovenkrands, Ryan Taylor, Kadar.
SHEFF WED 2 NEWCASTLE 2 (Nolan, Ameobi)
Harper, Simpson, Coloccini, Steven Taylor, Jose Enrique, Guthrie, Nolan, Butt, Gutierrez (Pancrate 64),Harewood (Lovenkrands 84), Ameobi (Carroll 73).
Subs Not Used: Krul, Ryan Taylor, Kadar, Ranger.
NEWCASTLE 0 DERBY COUNTY 0
Harper, Simpson, Steven Taylor, Coloccini, Jose Enrique, Ryan Taylor (Pancrate 70), Nolan, Smith, Gutierrez, Lovenkrands (Ranger 78), Carroll (Ameobi 65).
Subs Not Used: Krul, Guthrie, Butt, Kadar.
FA CUP: PLYMOUTH 0 NEWCASTLE 0
Krul, Simpson, Kadar, Coloccini, Ryan Taylor, Pancrate (Lovenkrands 79), Butt, Smith (Gutierrez 71), Guthrie, Ameobi, Ranger (Carroll 68).
Subs Not Used: Harper, Jose Enrique, Tozer, Donaldson.
FA CUP: NEWCASTLE 3 PLYMOUTH 0 (Lovenkrands 3)
Krul, Ryan Taylor, Steven Taylor, Coloccini,Jose Enrique, Pancrate (Guthrie 70), Nolan, Butt (Ranger 75),Gutierrez, Carroll, Lovenkrands (Donaldson 88).
Subs Not Used: Harper, Ameobi, Tozer, Ferguson.
NEWCASTLE 2 WEST BROM 2 (Guthrie, Lovenkrands)
Harper, Simpson (Ryan Taylor 85), Steven Taylor, Coloccini, Jose Enrique, Guthrie, Smith, Nolan, Gutierrez,Lovenkrands, Ameobi (Carroll 78).
Subs Not Used: Krul, Pancrate, Butt, Kadar, Ranger.
FA CUP: WEST BROM 4 NEWCASTLE 2 (Carroll 2)
Krul, Ryan Taylor, Coloccini, Kadar, Jose Enrique,Gutierrez, Smith, Guthrie (Donaldson 81), Pancrate (Ameobi 46),Nolan, Carroll, Ameobi (Ranger 79).
Subs Not Used: Harper, LuaLua, Tozer, Ferguson.
NEWCASTLE 2 CRYSTAL PALACE 0 (Derry og, Ranger)
Harper, Kadar, Williamson, Coloccini,Jose Enrique (Pancrate 25), Guthrie, Nolan, Smith,Gutierrez (Ranger 73), Carroll, Lovenkrands (Routledge 62).
Subs Not Used: Krul, Butt, Tozer, Donaldson.
LEICESTER 0 NEWCASTLE 0
Harper, Van Aanholt, Williamson, Coloccini,Ryan Taylor, Guthrie, Smith (Ranger 62), Butt, Routledge,Nolan (Pancrate 75), Carroll.
Subs Not Used: Krul, Hall, Lovenkrands, Gutierrez, Kadar.
NEWCASTLE 5 CARDIFF 1 (Carroll 2, Gyepes og, Lovenkrands 2)
Harper, Simpson, Williamson, Hall (Kadar 82), Van Aanholt, Routledge, Guthrie, Nolan, Gutierrez (Ryan Taylor 79), Carroll, Best (Lovenkrands 60).
Subs Not Used: Krul, Pancrate, Ameobi, Ranger.
DERBY 3 NEWCASTLE 0
Harper, Simpson, Williamson, Hall, Van Aanholt (Smith 67), Routledge, Nolan, Guthrie, Gutierrez, Carroll (Ameobi 67), Best (Lovenkrands 67).
Subs Not Used: Krul, Pancrate, Kadar, Donaldson.
SWANSEA 1 NEWCASTLE 1 (Carroll)
Harper, Coloccini, Hall, Simpson, Van Aanholt, Guthrie, Nolan, Routledge, Smith, Lovenkrands (Best 66), Carroll.
Subs Not Used: Krul, Williamson, Ryan Taylor, Pancrate, Kadar, Ranger.