Dorobou to Keiji (1997)

In a place that appears to be London/England, Police Officer Hugo, a serious young detective, seems to have been in pursuit of the bizarre and lighthearted thief named Dr. Martin for quite some time (who seems to have no clear motive or need to be a thief, except maybe boredom). Hugo wants to be the one to arrest him after chasing him for so long. However, the chase hits a turning point when Dr. Martin confesses that he became a thief just so he could catch Hugo’s attention... because he says he loves Hugo. Hugo still wants to arrest Martin, but with Martin’s confession, he doesn’t know what to do about the recent turn of events... or what to do about his own feelings. Meanwhile, Martin waits patiently for Hugo to come around...

Source: www.anisearch.com/manga/2370