Here's a snapshot of what I think was published for the first time in January 2024 (and is usually a UK date but occasionally will be a US or Australian date). 110 titles this month. If I've missed anything or got the date wrong, do please leave a comment.
Please note that, unless specifically mentioned, when a book has differing print and ebook release date, I use the print release date. Translators' names are included where known.
Armstrong, Jess - The Curse of Penryth Hall
Bailey, Jaye - The Killing Pages #3 DCI Luke Wiley
Barnes, Charlotte - A True Crime
Baylis, Edie - Trusting Blood #3 Scarred
Bettany, Jane - Murder at the Book Festival #2 Violet Brewster
Black, Katherine - A Most Malicious Messenger #2 Most Unusual Mysteries
Blake, Sam - Three Little Birds
Boland, Shalini - The School Reunion
Brett, Simon - Blotto, Twinks and the Phantom Skiers #13 Brother and sister sleuths, Blotto and Twinks
Brook, Lee - The Echoes of Silence #14 West Yorkshire Crime
Brookes, Dawn - Murder in a Care Home #5 Lady Marjorie Snellthorpe
Bull, Jessica - Miss Austen Investigates #1 Miss Austen Investigates
Butler, D S - Before the Dawn #8 DS Karen Hart, Lincolnshire
Clements, Rory - Munich Wolf
Comley, M A - Revenge Streak #22 DI Sara Ramsey
Connelly, Lucy - Death at a Scottish Wedding #2 Dr Emilia McRoy
Critchlow, Heather - Unburied #2 Cal Lovett Files
Croft, Kathryn - The Girl in Room 12
Dalgliesh, J M - The Talisker Dead #3 DI Duncan McAdam, Isle of Skye
de la Motte, Anders - The Mountain King tr. Alex Fleming #1 Criminal inspector Leonore Asker
Devlin, Cara - Nature of the Crime #6 Bow Street Duchess
East, Philippa - A Guilty Secret
Ellis, Emmy - Reflect #24 Cardigan Estate
Ellis, Emmy - The Blade Killer #8 DI Bethany Smith
Ellis, Emmy - The Sledgehammer Killer #9 DI Bethany Smith
Ellis, Joy - An Aura of Mystery #1 Ellie McEwan
Enright, Robert - Blood Money #13 Sam Pope
Ferraro, Nicolás - My Favorite Scar tr. Mallory Craig-Kuhn
FitzGerald, Helen - Halfway House
Galloway, K T - Still Waters #8 O'Malley & Swift
Goodwin, Sarah - The Yacht
Grace, Fiona - A Scandalous Death #2 The Maid and the Mansion
Graham, R L - Death on the Lusitania
Grayson, C J - Taken From Her Home #1 Detective April Fisher
Greig, Andrew James - The Girl in the Loch #1 Private Investigator Tearlach Paterson, Scotland
Griffiths, Elly - The Last Word
Hall, Araminta - One of the Good Guys
Hall, Traci - Murder at a Scottish Castle #5 Paislee Shaw, Nairn, Scotland
Hannah, Mari - The Longest Goodbye #9 Detective Chief Inspector Kate Daniels
Hindle, Tom - Murder on Lake Garda
Hood, D K - A Song for the Dead #21 Detectives Kane and Alton
Howard, B M - Blood of the Knights #3 Gracchus & Vanderville
Hunter, E V - A Story to Strangle For #4 Hopgood Hall Murder Mysteries
Hurst, Daniel - The Couple's Revenge
Jackson, Gillian - The Dead Husband
James, Evelyn - Death at the Sun Club #31 Clara Fitzgerald
Jenkins, Victoria - Your Perfect Life
Jensen, Oskar - Helle and Death
Johnston, Anthony - The Dog Sitter Detective Takes the Lead #2 Gwinny Tuffel, Dog sitter
Jordan, G R - Death of the Witch (ebook only) #2 Siobhan Duffy
Kidd, Michelle - Three Broken Bodies #5 DI Jack MacIntosh
Kildare, Kitty - Death at the Fireside Inn #1 Veronica Vale, 1920s
Kinder, Gomery - London Lies Bleeding #1 Justin Martello
Kitson, Bill - Death Sentence #17 Detective Mike Nash, Yorkshire
Kovach, Carla - On a Quiet Street
Lane, Anna Sayburn - The Soho Jazz Murders #2 Marjorie, 1920s
Lewis, J G- Unholy Sanctuary #10 Ela of Salisbury Medieval Mystery
MacLeod, Shéa - Lady Rample and the Lady in the Lake #12 Lady Rample, 1930s
Mancini, Ruth - The Woman on the Ledge
Marlow, Natalie - The Red Hollow #2 William Garrett, Birmingham
Marston, Edward - Murder in Transit #22 Det. Insp Colbeck, Scotland Yard, mid 19th Century
Martin, Faith - Murder by Candlelight
Maslen, Andy - The Seventh Girl #1 Detective Kat Ballantyne
Mason, Simon - Lost and Never Found #3 DI Ray Wilkins, Oxford
McCleave, Simon - The Drowning Isle #4 DCI Laura Hart, Anglesey
McIlroy, Alice - The Glass Woman
McLean, Rachel & Joel Hames - The Mine #2 Cumbria Crime
Morrison, Lynn - The Roman Riddle #5 Dora and Rex, 1920s
Mróz, Remigiusz - Final Appeal tr. ??? #1 Joanna Chylka, Lawyer
Murphy, Martina - The Reckoning #3 DS Lucy Golden
O'Brien, Jenny - Roses for the Dead #2 Detective Alana Mack
Organ, Emily - Murder on the Thames #6 Augusta Peel, 1920s
Pearce, Biba & L T Ryan - The Frost Killer #4 Dalton Savage
Probyn, Jack - Death's Kiss #4 DS Tomek Bowen
Quinn, Cate - The Clinic
Reed, HJ - A Fatal Pact#3 DI Crow
Reynolds, Amanda - The Screenwriter
Richards, Mark & E S Richards - The Hanged Woman #6 Michael Brady, Yorkshire
Richell, Hannah - The Search Party
Rigby, Sally - The Hidden Graves of St Ives #2 Detective Lauren Pengelly & Detective Matt Price
Robertson, C S - The Trials of Marjorie Crowe
Rose, M L - Looking For You #6 DCI Rohan Roy
Rosett, Sara - Murder in the Alps #8 High Society Lady Detective, 1920s England
Russell, Leigh - Poppy Takes the Lead #3 Poppy Mystery
Ryan, Sadie - The Proposal
Ryan, Sadie - The Secretary
Salter, Michelle - Murder at Merewood Hospital
Saxon, Diane - The Good Twin
Seymour, Gerald - The Best Revenge #4 Jonas Merrick
Skuse, C J - Thorn In My Side #4 Sweetpea
Stacey, L H - The Accident
Sullivan, Tim - The Teacher #6 DS Cross, Bristol
Tait, Victoria - Vanilla Chai and a Vanishing Victim #3 Waterwheel Café
Taylor, Stephen - Won't Stay Dead #10 Danny Pearson
Thorogood, Robert - The Queen of Poisons #3 The Marlow Murder Club
Vickery, Sam - The Child at My Door
Vingtras, Marie - Blizzard tr. Stephanie Smee
Weatherley, Anna-Lou - The Housewife's Secret #7 Detective Dan Riley
Webb, Kate - Laying Out the Bones #2 Detective Inspector Matt Lockyer, Wiltshire
Wells, Kate - Stranger in the Village #2 Jude Gray
Welsh, Louise - To the Dogs
Westerson, Jeri - The Twilight Queen #2 King's Fool
Wilkinson, Diana - The Girl in Seat 2a
Wilson, Edward - Farewell Dinner for a Spy #8 Catesby
Wingate, Marty - A Body on the Doorstep #1 London Ladies' Murder Club
Wingate, Marty - A Body at the Séance #2 London Ladies' Murder Club
Wray, C J - The Excitements
Wyer, Carol - A Soul for a Soul #5 DI Kate Young, Staffordshire
Young, Debbie - Driven to Murder #9 Sophie Sayers