In this age when most organizations make use of cloud computing, it is important to not only protect cloud computing resources from cyber-attacks but also investigate these attacks. During forensic investigations in a cloud environment, the investigators fall on service providers for pieces of evidence like log files. The challenge, however, is the integrity of these logs provided by the service providers. To this end, we propose a blockchain-based log verification system called BlogVerifier that uses a decentralized approach to solve forensics issues in the cloud. BlogVerifier extracts logs produced in cloud environments, hashes these logs and stores the hashed values as transactional values on the blockchain. The transactions are then merged into blocks and shared on the blockchain. The proposed system also ensures the continuation of an investigation even when the primary source of a log is compromised by using encryption and smart contracts. The proposed system also makes it possible for any stakeholder involved in the forensic process to verify the authenticity of log files. The performance results show that BlogVerifier can be integrated into the cloud environment without any significant impact on system resources and increase in computational cost.