WASHINGTON—The House Intelligence Committee has finished interviewing witnesses in its yearlong probe into Russian interference in the 2016 election, according to a person familiar with the matter, signaling the end is near of a contentious investigation that has revealed deep partisan divisions on the panel.

The Republican-run committee is now preparing to write a report based on the testimony of dozens of witnesses and thousands of pages of documents. Republicans and Democrats on the panel are unlikely to come to a bipartisan...