Me and my roompartner decide to buy a book costing 3000 by puting in half the money each(1500 each). the book is left with me, i dont want to keep it all for my self because he also had contributed

I stayed in a hostel with my roompartner. After sometime many persons including me boycotted my roompartner because he used to steal things. After i completed my studies i returned to my city and my roompartner went back to his city. Now that book is left with me and i dont want to keep it all for my self because he also had contributed half the money for purchasing it and has a share in it. It is possible to get my roompartners telephone number from a friend of mine who is his neighbour. However i dont want to get in touch with him. Please advise me what to do with this book. If however it is necessary according to Islamic Laws i will contact him and ask him what to do with the book. Please advise contacting him if it is the only solution.